chore(deps + error): apply changes from deps and moved to failure

25 files changed, 968 insertions, 628 deletions

diff --git a/Cargo.toml b/Cargo.toml
index 6e224b7..5c822e7 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,31 +1,32 @@
 [package]
+name = "mail-template"
+version = "0.2.0"
+description = "[internal/mail-api] provides a \"composition through template\"  api for the Mail type from the mail-api crates"
 authors = ["Philipp Korber <p.korber@1aim.com>"]
+keywords = ["mail-api", "internal"]
 categories = []
-description = "TODO"
-documentation = "https://docs.rs/mail-codec-composition"
-keywords = ["mail", "codec", "mime", "smtp"]
 license = "MIT OR Apache-2.0"
-name = "mail-codec-composition"
 readme = "./README.md"
-repository = "https://github.com/1aim/mail-codec-composition"
-version = "0.1.0"
+documentation = "https://docs.rs/mail-template"
+repository = "https://github.com/1aim/mail-template"
 
 
 [dependencies]
+mail-type = { git="https://github.com/1aim/mail-codec" }
+mail-common = { git="https://github.com/1aim/mail-common" }
+mail-headers = { git="https://github.com/1aim/mail-headers" }
+
+failure = "0.1.1"
 futures = "0.1.14"
 log = "0.3.8"
 rand = "0.3.15"
 scoped-tls = "0.1.0"
 serde = "1.0.10"
 serde_derive = "1.0.10"
-vec1 = { git="https://github.com/1aim/vec1" }
-total-order-multi-map = { git="https://github.com/1aim/total-order-multi-map" }
-mail-codec = { git="https://github.com/1aim/mail-codec" }
-mail-codec-core = { git="https://github.com/1aim/mail-codec-core" }
-mail-codec-headers = { git="https://github.com/1aim/mail-codec-headers" }
-error-chain = "0.11.0"
 chrono = "0.4.0"
+vec1 = { git="https://github.com/1aim/vec1" }
 soft-ascii-string = "0.2.0"
+
 futures-cpupool = { version = "0.1.5", optional = true }
 tera = { version = "0.11.1", optional = true }
 conduit-mime-types = { version = "0.7.3", optional = true}
@@ -45,15 +46,19 @@ regex = "0.2.6"
 debug_trace_tokens = []
 render-template-engine = ["conduit-mime-types", "lazy_static"]
 tera-bindings = ["tera", "render-template-engine"]
-default = ["default_impl"]
-default_impl = [
-    "default_impl_name_composer", "default_impl_component_id", "default_impl_simple_context"
+
+default = [
+    "default_impl_name_composer",
+    "default_impl_component_id",
+    "default_impl_simple_context"
 ]
 default_impl_name_composer = []
 default_impl_component_id = []
 default_impl_simple_context = [
-    "default_impl_component_id", "mail-codec/default_impl_fs", "mail-codec/default_impl_cpupool",
+    "default_impl_component_id",
+    "mail-type/default_impl_fs",
+    "mail-type/default_impl_cpupool",
     "futures-cpupool"
 ]
 
-traceing = [ "mail-codec/traceing" ]
+traceing = [ "mail-type/traceing" ]
\ No newline at end of file
diff --git a/README.md b/README.md
index 6467894..c866805 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,5 @@
 
-# mail-codec-composition &emsp; [![Build Status](https://travis-ci.org/1aim/mail_codec.svg?branch=master)](https://travis-ci.org/1aim/mail_codec)
+# mail-template &emsp; [![Build Status](https://travis-ci.org/1aim/mail_type.svg?branch=master)](https://travis-ci.org/1aim/mail_type)
 
 **TODO**
 
@@ -8,7 +8,7 @@
 TODO
 
 
-Documentation can be [viewed on docs.rs](https://docs.rs/mail-codec-composition).
+Documentation can be [viewed on docs.rs](https://docs.rs/mail-template).
 
 
 ## License
diff --git a/examples/composition.rs b/__examples/composition.rs
index 1286068..38a7da3 100644
--- a/examples/composition.rs
+++ b/__examples/composition.rs
@@ -1,8 +1,8 @@
 //
 // !! YOU MIGHT WANT TO TAKE A LOOK AT tests/tera/main.rs WHICH IS A BETTER EXAMPLE !!
 //
-extern crate mail_codec as mail;
-extern crate mail_codec_composition as compose;
+extern crate mail_type as mail;
+extern crate mail_template as compose;
 extern crate futures;
 extern crate mime;
 extern crate serde;
diff --git a/src/builder_extension.rs b/src/builder_extension.rs
index edf9956..29e5343 100644
--- a/src/builder_extension.rs
+++ b/src/builder_extension.rs
@@ -1,16 +1,15 @@
 use media_type::{MULTIPART, ALTERNATIVE, RELATED, MIXED};
 use vec1::Vec1;
 
-use core::error::{Result, ErrorKind};
-use core::header::HeaderMap;
 
-use headers::{ContentId, ContentDisposition};
-use headers::components::Disposition;
-use mail::MediaType;
+use headers::{HeaderMap, ContentId, ContentDisposition};
+use headers::components::{Disposition, MediaType};
 use mail::{Resource, Mail, Builder};
+use mail::error::OtherBuilderErrorKind;
 
-use template::BodyPart;
-use resource::{EmbeddingWithCId,  Attachment};
+use ::template::BodyPart;
+use ::resource::{EmbeddingWithCId,  Attachment};
+use ::error::{ExtendedBuilderError, ExtendedBuilderErrorKind};
 
 
 /// Ext. Trait which adds helper methods to the Builder type.
@@ -20,34 +19,34 @@ pub trait BuilderExt {
     fn create_alternate_bodies<HM>(
         bodies: Vec1<BodyPart>,
         header: HM
-    ) -> Result<Mail>
+    ) -> Result<Mail, ExtendedBuilderError>
         where HM: Into<Option<HeaderMap>>;
 
 
     fn create_mail_body<HM>(
         body: BodyPart,
         headers: HM
-    ) -> Result<Mail>
+    ) -> Result<Mail, ExtendedBuilderError>
         where HM: Into<Option<HeaderMap>>;
 
     fn create_with_attachments<HM>(
         body: Mail,
         attachments: Vec<Attachment>,
         headers: HM
-    ) -> Result<Mail>
+    ) -> Result<Mail, ExtendedBuilderError>
         where HM: Into<Option<HeaderMap>>;
 
     fn create_body_from_resource<HM>(
         resource: Resource,
         headers: HM
-    ) -> Result<Mail>
+    ) -> Result<Mail, ExtendedBuilderError>
         where HM: Into<Option<HeaderMap>>;
 
     fn create_body_with_embeddings<HM, EMB>(
         sub_body: Mail,
         embeddings: EMB,
         headers: HM
-    ) -> Result<Mail>
+    ) -> Result<Mail, ExtendedBuilderError>
         where HM: Into<Option<HeaderMap>>,
               EMB: Iterator<Item=EmbeddingWithCId> + ExactSizeIterator;
 
@@ -55,7 +54,7 @@ pub trait BuilderExt {
         bodies: Vec1<BodyPart>,
         embeddings: EMB,
         header: HM
-    ) -> Result<Mail>
+    ) -> Result<Mail, ExtendedBuilderError>
         where HM: Into<Option<HeaderMap>>,
               EMB: Iterator<Item=EmbeddingWithCId> + ExactSizeIterator;
 }
@@ -67,45 +66,45 @@ impl BuilderExt for Builder {
     fn create_alternate_bodies<HM>(
         bodies: Vec1<BodyPart>,
         headers: HM
-    ) -> Result<Mail>
+    ) -> Result<Mail, ExtendedBuilderError>
         where HM: Into<Option<HeaderMap>>
     {
         let bodies = bodies;
 
         match bodies.len() {
-            0 => bail!( ErrorKind::NeedAtLastOneBodyInMultipartMail ),
-            1 => return Self::create_mail_body(bodies.into_vec().pop().unwrap(), headers ),
+            0 => return Err(OtherBuilderErrorKind::EmptyMultipartBody.into()),
+            1 => return Self::create_mail_body(bodies.into_vec().pop().unwrap(), headers),
             _n => {}
         }
 
         let mut builder = Builder::multipart(MediaType::new(MULTIPART, ALTERNATIVE)?)?;
 
         if let Some(headers) = headers.into() {
-            builder = builder.headers( headers )?;
+            builder = builder.headers(headers)?;
         }
 
         for body in bodies {
-            builder = builder.body( Self::create_mail_body( body, None )? )?;
+            builder = builder.body(Self::create_mail_body(body, None)?)?;
         }
 
-        builder.build()
+        Ok(builder.build()?)
     }
 
     fn create_alternate_bodies_with_embeddings<HM, EMB>(
         bodies: Vec1<BodyPart>,
         embeddings: EMB,
         headers: HM
-    ) -> Result<Mail>
+    ) -> Result<Mail, ExtendedBuilderError>
         where HM: Into<Option<HeaderMap>>,
               EMB: Iterator<Item=EmbeddingWithCId> + ExactSizeIterator
     {
         match embeddings.len() {
             0 => {
-                Self::create_alternate_bodies( bodies, headers )
+                Self::create_alternate_bodies(bodies, headers)
             },
             _n => {
                 Self::create_body_with_embeddings(
-                    Self::create_alternate_bodies( bodies, None )?,
+                    Self::create_alternate_bodies(bodies, None)?,
                     embeddings,
                     headers
                 )
@@ -116,65 +115,65 @@ impl BuilderExt for Builder {
     fn create_mail_body<HM>(
         body: BodyPart,
         headers: HM
-    ) -> Result<Mail>
+    ) -> Result<Mail, ExtendedBuilderError>
         where HM: Into<Option<HeaderMap>>
     {
         let BodyPart { body_resource, embeddings } = body;
         if embeddings.len() > 0 {
             Self::create_body_with_embeddings(
-                Self::create_body_from_resource( body_resource, None )?,
+                Self::create_body_from_resource(body_resource, None)?,
                 embeddings.into_iter(),
                 headers
             )
         } else {
-            Self::create_body_from_resource( body_resource, headers )
+            Self::create_body_from_resource(body_resource, headers)
         }
     }
 
     fn create_body_from_resource<HM>(
         resource: Resource,
         headers: HM
-    ) -> Result<Mail>
+    ) -> Result<Mail, ExtendedBuilderError>
         where HM: Into<Option<HeaderMap>>
     {
-        let mut builder = Builder::singlepart( resource );
-        if let Some( headers ) = headers.into() {
-            builder = builder.headers( headers )?;
+        let mut builder = Builder::singlepart(resource);
+        if let Some(headers) = headers.into() {
+            builder = builder.headers(headers)?;
         }
-        builder.build()
+        Ok(builder.build()?)
     }
 
     fn create_body_with_embeddings<HM, EMB>(
         sub_body: Mail,
         embeddings: EMB,
         headers: HM
-    ) -> Result<Mail>
+    ) -> Result<Mail, ExtendedBuilderError>
         where HM: Into<Option<HeaderMap>>,
               EMB: Iterator<Item=EmbeddingWithCId> + ExactSizeIterator
     {
 
         if embeddings.len() == 0 {
-            bail!( "this function except at last one embedding" )
+            return Err(ExtendedBuilderErrorKind::EmbeddingMissing.into());
         }
 
-        let mut builder = Builder::multipart( MediaType::new(MULTIPART,RELATED)?)?;
+        let mut builder = Builder::multipart(MediaType::new(MULTIPART,RELATED)?)?;
 
-        if let Some( headers ) = headers.into() {
-            builder = builder.headers( headers )?;
+        if let Some(headers) = headers.into() {
+            builder = builder.headers(headers)?;
         }
 
 
-        builder = builder.body( sub_body )?;
+        builder = builder.body(sub_body)?;
         for embedding in embeddings {
-            let ( content_id, resource ) = embedding.into();
+            let (content_id, resource) = embedding.into();
             builder = builder.body(
-                Self::create_body_from_resource( resource , headers! {
+                Self::create_body_from_resource(resource , headers! {
                     ContentId: content_id,
                     ContentDisposition: Disposition::inline()
-                }? )?
+                }?)?
             )?;
         }
-        builder.build()
+        Ok(builder.build()?)
     }
 
 
@@ -182,28 +181,28 @@ impl BuilderExt for Builder {
         body: Mail,
         attachments: Vec<Attachment>,
         headers: HM
-    )  -> Result<Mail>
+    )  -> Result<Mail, ExtendedBuilderError>
         where HM: Into<Option<HeaderMap>>
     {
 
         let mut builder = Builder::multipart(MediaType::new(MULTIPART, MIXED)?)?;
 
-        if let Some( headers ) = headers.into() {
-            builder = builder.headers( headers )?;
+        if let Some(headers) = headers.into() {
+            builder = builder.headers(headers)?;
         }
 
-        builder = builder.body( body )?;
+        builder = builder.body(body)?;
 
         for attachment in attachments {
-            builder = builder.body( Self::create_body_from_resource(
+            builder = builder.body(Self::create_body_from_resource(
                 attachment.into(),
                 headers! {
                     ContentDisposition: Disposition::attachment()
                 }?
-            )? )?;
+            )?)?;
         }
 
-        builder.build()
+        Ok(builder.build()?)
     }
 }
 
diff --git a/src/compositor/_impl.rs b/src/compositor/_impl.rs
index 8bb83bf..9fa803c 100644
--- a/src/compositor/_impl.rs
+++ b/src/compositor/_impl.rs
@@ -3,22 +3,23 @@ use std::borrow::Cow;
 use serde::Serialize;
 use vec1::Vec1;
 
-use core::utils::HeaderTryFrom;
-use core::error::{Result, ResultExt};
-use core::header::HeaderMap;
-use headers::{From, To, Subject, Sender};
+use headers::{
+    HeaderMap, HeaderTryFrom,
+    _From, _To, Subject, Sender
+};
 use headers::components::Unstructured;
 use mail::{Mail, Builder};
 
-use utils::SerializeOnly;
-use resource::{
+use ::utils::SerializeOnly;
+use ::resource::{
     EmbeddingWithCId, Attachment,
     with_resource_sidechanel
 };
-use builder_extension::BuilderExt;
-use template::{
+use ::builder_extension::BuilderExt;
+use ::template::{
     BodyPart, TemplateEngine, MailParts
 };
+use ::error::CompositionError;
 
 use super::mail_send_data::MailSendData;
 use super::{CompositionBase, EnvelopData};
@@ -27,9 +28,12 @@ pub(crate) trait InnerCompositionBaseExt: CompositionBase {
 
     fn _compose_mail<D>(
         &self,
-        send_data:
-            MailSendData<<Self::TemplateEngine as TemplateEngine<Self::Context>>::TemplateId, D>
-    ) -> Result<(Mail, EnvelopData)>
+        send_data: MailSendData<
+            <Self::TemplateEngine as TemplateEngine<Self::Context>>::TemplateId, D>
+    ) -> Result<
+        (Mail, EnvelopData),
+        CompositionError<<Self::TemplateEngine as TemplateEngine<Self::Context>>::Error>
+    >
         where D: Serialize
     {
         let envelop = EnvelopData::from(&send_data);
@@ -39,8 +43,8 @@ pub(crate) trait InnerCompositionBaseExt: CompositionBase {
         let MailParts { alternative_bodies, shared_embeddings, attachments }
             = self.use_template_engine(&*template_id, data)?;
 
-        let mail = self.build_mail( alternative_bodies, shared_embeddings.into_iter(),
-                                    attachments, core_headers )?;
+        let mail = self.build_mail(alternative_bodies, shared_embeddings.into_iter(),
+                                    attachments, core_headers)?;
 
         Ok((mail, envelop))
     }
@@ -53,7 +57,7 @@ pub(crate) trait InnerCompositionBaseExt: CompositionBase {
         HeaderMap,
         D,
         Cow<'a, <Self::TemplateEngine as TemplateEngine<Self::Context>>::TemplateId>
-    )>
+    ), CompositionError<<Self::TemplateEngine as TemplateEngine<Self::Context>>::Error>>
         where D: Serialize
     {
         let (sender, from_mailboxes, to_mailboxes, subject, template_id, data)
@@ -62,12 +66,12 @@ pub(crate) trait InnerCompositionBaseExt: CompositionBase {
         // The subject header field
         let subject = Unstructured::try_from( subject )?;
 
-        // createing the header map
+        // creating the header map
         let mut core_headers: HeaderMap = headers! {
-            //NOTE: if we support multiple mailboxes in From we have to
+            //NOTE: if we support multiple mailboxes in _From we have to
             // ensure Sender is used _iff_ there is more than one from
-            From: from_mailboxes,
-            To: to_mailboxes,
+            _From: from_mailboxes,
+            _To: to_mailboxes,
             Subject: subject
         }?;
 
@@ -84,22 +88,22 @@ pub(crate) trait InnerCompositionBaseExt: CompositionBase {
         template_id: &<Self::TemplateEngine as TemplateEngine<Self::Context>>::TemplateId,
         //TODO change to &D?
         data: D
-    ) -> Result<MailParts>
+    ) -> Result<MailParts, CompositionError<<Self::TemplateEngine as TemplateEngine<Self::Context>>::Error>>
         where D: Serialize
     {
         let id_gen = Box::new(self.context().clone());
         let ( mut mail_parts, embeddings, attachments ) =
-            with_resource_sidechanel(id_gen, || -> Result<_> {
+            with_resource_sidechanel(id_gen, || -> Result<_, CompositionError<<Self::TemplateEngine as TemplateEngine<Self::Context>>::Error>> {
                 // we just want to make sure that the template engine does
                 // really serialize the data, so we make it so that it can
                 // only do so (if we pass in the data directly it could use
-                // TypeID+Transmut or TraitObject+downcast to undo the generic
+                // TypeID+Transmute or TraitObject+downcast to undo the generic
                 // type erasure and then create the template in some other way
                 // but this would break the whole Embedding/Attachment extraction )
                 let sdata = SerializeOnly::new(data);
                 self.template_engine()
                     .use_templates(self.context(), template_id, &sdata)
-                    .chain_err(|| "failure in template engine")
+                    .map_err(|err| CompositionError::Template(err))
             })?;
 
         mail_parts.attachments.extend(attachments);
@@ -110,25 +114,25 @@ pub(crate) trait InnerCompositionBaseExt: CompositionBase {
 
 
     /// uses the results of preprocessing data and templates, as well as a list of
-    /// mail headers like `From`,`To`, etc. to create a new mail
+    /// mail headers like `_From`,`To`, etc. to create a new mail
     fn build_mail<EMB>(&self,
                        bodies: Vec1<BodyPart>,
                        embeddings: EMB,
                        attachments: Vec<Attachment>,
                        core_headers: HeaderMap
-    ) -> Result<Mail>
+    ) -> Result<Mail, CompositionError<<Self::TemplateEngine as TemplateEngine<Self::Context>>::Error>>
         where EMB: Iterator<Item=EmbeddingWithCId> + ExactSizeIterator
     {
         let mail = match attachments.len() {
             0 => Builder::create_alternate_bodies_with_embeddings(
-                bodies, embeddings, Some(core_headers) )?,
+                bodies, embeddings, Some(core_headers))?,
             _n => Builder::create_with_attachments(
-                Builder::create_alternate_bodies_with_embeddings(bodies, embeddings, None )?,
+                Builder::create_alternate_bodies_with_embeddings(bodies, embeddings, None)?,
                 attachments,
-                Some( core_headers )
+                Some(core_headers)
             )?
         };
-        Ok( mail )
+        Ok(mail)
     }
 }
 
diff --git a/src/compositor/mail_send_data.rs b/src/compositor/mail_send_data.rs
index 9ff9d04..8a9087e 100644
--- a/src/compositor/mail_send_data.rs
+++ b/src/compositor/mail_send_data.rs
@@ -6,13 +6,15 @@ use std::fmt::{self, Debug};
 use serde::Serialize;
 use vec1::Vec1;
 
-use error::Error;
-use core::HeaderTryFrom;
-use mail::headers::components::{
+use headers::HeaderTryFrom;
+use headers::error::ComponentCreationError;
+use headers::components::{
     Mailbox, MailboxList,
     Phrase, Email
 };
 
+use ::error::{MailSendDataError, MailSendDataErrorKind, WithSource, WithSourceExt};
+
 /// A type containing all per-Mail specific information
 ///
 /// The contained information is:
@@ -37,13 +39,14 @@ use mail::headers::components::{
 /// # Example (Construction)
 ///
 /// ```
-/// # extern crate mail_codec as mail;
-/// # extern crate mail_codec_composition as compose;
-/// # extern crate mail_codec_core as core;
+/// # extern crate mail_common as common;
+/// # extern crate mail_headers as headers;
+/// # extern crate mail_type as mail;
+/// # extern crate mail_template as compose;
 /// # use std::collections::HashMap;
+/// # use headers::HeaderTryFrom;
+/// # use headers::components::{Mailbox, Email};
 /// # use compose::MailSendDataBuilder;
-/// # use mail::headers::components::{Mailbox, Email};
-/// # use core::HeaderTryFrom;
 /// #
 /// # fn main() {
 /// #
@@ -175,7 +178,7 @@ impl<'a, TId: ?Sized + 'a, D> MailSendData<'a, TId, D>
         (sender, from, to, subject, template_id, data)
     }
 
-    pub fn auto_gen_display_names<NC>(&mut self, name_composer: NC) -> Result<(), Error>
+    pub fn auto_gen_display_names<NC>(&mut self, name_composer: NC) -> Result<(), ComponentCreationError>
         where NC: NameComposer<D>
     {
         let data = &mut self.data;
@@ -226,7 +229,7 @@ pub trait NameComposer<D> {
     /// _not_ be returned if there is "just" not enough data to create a display
     /// name, in which `Ok(None)` should be returned indicating that there is
     /// no display name.
-    fn compose_from_name( &self, email: &Email, data: &mut D ) -> Result<Option<String>, Error>;
+    fn compose_from_name( &self, email: &Email, data: &mut D ) -> Result<Option<String>, ComponentCreationError>;
 
     /// generates a display name used in a To header based on email address and mails data
     /// The data is passed in as a `&mut` ref so that the generated name can
@@ -243,17 +246,17 @@ pub trait NameComposer<D> {
     /// _not_ be returned if there is "just" not enough data to create a display
     /// name, in which `Ok(None)` should be returned indicating that there is
     /// no display name.
-    fn compose_to_name( &self, email: &Email, data: &mut D ) -> Result<Option<String>, Error>;
+    fn compose_to_name( &self, email: &Email, data: &mut D ) -> Result<Option<String>, ComponentCreationError>;
 
 }
 
 impl<D, T> NameComposer<D> for Arc<T>
     where T: NameComposer<D>, D: Serialize
 {
-    fn compose_from_name( &self, email: &Email, data: &mut D ) -> Result<Option<String>, Error> {
+    fn compose_from_name( &self, email: &Email, data: &mut D ) -> Result<Option<String>, ComponentCreationError> {
         self.deref().compose_from_name(email, data)
     }
-    fn compose_to_name( &self, email: &Email, data: &mut D ) -> Result<Option<String>, Error> {
+    fn compose_to_name( &self, email: &Email, data: &mut D ) -> Result<Option<String>, ComponentCreationError> {
         self.deref().compose_to_name(email, data)
     }
 }
@@ -261,10 +264,10 @@ impl<D, T> NameComposer<D> for Arc<T>
 impl<D, T> NameComposer<D> for Box<T>
     where T: NameComposer<D>, D: Serialize
 {
-    fn compose_from_name( &self, email: &Email, data: &mut D ) -> Result<Option<String>, Error> {
+    fn compose_from_name( &self, email: &Email, data: &mut D ) -> Result<Option<String>, ComponentCreationError> {
         self.deref().compose_from_name(email, data)
     }
-    fn compose_to_name( &self, email: &Email, data: &mut D ) -> Result<Option<String>, Error> {
+    fn compose_to_name( &self, email: &Email, data: &mut D ) -> Result<Option<String>, ComponentCreationError> {
         self.deref().compose_to_name(email, data)
     }
 }
@@ -272,7 +275,7 @@ impl<D, T> NameComposer<D> for Box<T>
 
 /// Builder to create `MailSendData`
 pub struct MailSendDataBuilder<'a, TId: ?Sized + 'a, D>
-    where TId: ToOwned, D: Serialize
+    where TId: ToOwned + Debug, TId::Owned: Debug, D: Serialize + Debug
 {
     sender: Option<Mailbox>,
     from: Vec<Mailbox>,
@@ -283,7 +286,7 @@ pub struct MailSendDataBuilder<'a, TId: ?Sized + 'a, D>
 }
 
 impl<'a, TId: ?Sized + 'a, D> Debug for MailSendDataBuilder<'a, TId, D>
-    where TId: ToOwned + Debug, <TId as ToOwned>::Owned: Debug, D: Serialize + Debug
+    where TId: ToOwned + Debug, TId::Owned: Debug, D: Serialize + Debug
 {
     fn fmt(&self, fter: &mut fmt::Formatter) -> fmt::Result {
         fter.debug_struct("MailSendData")
@@ -300,7 +303,7 @@ impl<'a, TId: ?Sized + 'a, D> Debug for MailSendDataBuilder<'a, TId, D>
 // Sadly I can not used derive(Default) (it want's a bound on TId)
 // if the deriviate create is stable, I could use them for that
 impl<'a, TId: ?Sized + 'a, D> Default for MailSendDataBuilder<'a, TId, D>
-    where TId: ToOwned, D: Serialize
+    where TId: ToOwned + Debug, TId::Owned: Debug, D: Serialize + Debug
 {
     fn default() -> Self {
         Self::new()
@@ -308,7 +311,7 @@ impl<'a, TId: ?Sized + 'a, D> Default for MailSendDataBuilder<'a, TId, D>
 }
 
 impl<'a, TId: ?Sized + 'a, D> MailSendDataBuilder<'a, TId, D>
-    where TId: ToOwned, D: Serialize
+    where TId: ToOwned + Debug, TId::Owned: Debug, D: Serialize + Debug
 {
     pub fn new() -> Self {
         MailSendDataBuilder {
@@ -398,15 +401,18 @@ impl<'a, TId: ?Sized + 'a, D> MailSendDataBuilder<'a, TId, D>
     ///
     /// - no data, template_id, from or to was set
     /// - more than one from was set, but no sender was set
-    pub fn build(self) -> Result<MailSendData<'a, TId, D>, Self> {
-        if self.from.is_empty() || self.to.is_empty()
-            || self.subject.is_none() || self.template_id.is_none()
-            || self.data.is_none()
-        {
-            return Err(self)
+    pub fn build(self)
+        -> Result<MailSendData<'a, TId, D>, WithSource<MailSendDataError, Self>>
+    {
+        match self.check_fields_are_set() {
+            Ok(_) => {},
+            Err(err) => return Err(err.with_source(self))
         }
+
         if self.from.len() > 1 && self.sender.is_none() {
-            return Err(self)
+            return Err(MailSendDataError
+                ::from(MailSendDataErrorKind::MultiFromButNoSender)
+                .with_source(self));
         }
 
 
@@ -426,4 +432,24 @@ impl<'a, TId: ?Sized + 'a, D> MailSendDataBuilder<'a, TId, D>
             data
         })
     }
-}
\ No newline at end of file
+
+    fn check_fields_are_set(&self) -> Result<(), MailSendDataError> {
+        use self::MailSendDataErrorKind::*;
+        let kind =
+            if self.from.is_empty() {
+                MissingFrom
+            } else if self.to.is_empty() {
+                MissingTo
+            } else if self.subject.is_none() {
+                MissingSubject
+            } else if self.template_id.is_none() {
+                MissingTemplateId
+            } else if self.data.is_none() {
+                MissingTemplateData
+            } else {
+                return Ok(());
+            };
+
+        Err(MailSendDataError::from(kind))
+    }
+}
diff --git a/src/compositor/mod.rs b/src/compositor/mod.rs
index 8123f4a..c26101a 100644
--- a/src/compositor/mod.rs
+++ b/src/compositor/mod.rs
@@ -2,12 +2,12 @@ use std::borrow::ToOwned;
 
 use serde::Serialize;
 
-use error::Result;
-use context::Context;
-use template::TemplateEngine;
 use mail::Mail;
-use mail::headers::components::{MailboxList, Mailbox};
+use headers::components::{MailboxList, Mailbox};
 
+use ::context::Context;
+use ::template::TemplateEngine;
+use ::error::CompositionError;
 //TODO make sure Box/Arc auto wrapping is impl for all parts
 use self::_impl::InnerCompositionBaseExt;
 
@@ -36,7 +36,10 @@ pub trait CompositionBase {
         &self,
         send_data: MailSendData<
             <Self::TemplateEngine as TemplateEngine<Self::Context>>::TemplateId, D>
-    ) -> Result<(Mail, EnvelopData)>
+    ) -> Result<
+        (Mail, EnvelopData),
+        CompositionError<<Self::TemplateEngine as TemplateEngine<Self::Context>>::Error>
+    >
         where D: Serialize
     {
         InnerCompositionBaseExt::_compose_mail(self, send_data)
diff --git a/src/context.rs b/src/context.rs
index 62daf5d..a637a3a 100644
--- a/src/context.rs
+++ b/src/context.rs
@@ -1,20 +1,19 @@
 use futures::{Future, IntoFuture};
 
 use mail::utils::SendBoxFuture;
-use core::error::Result;
 use mail::context::{BuilderContext, Source, LoadResourceFuture};
-use headers::components::MessageID;
+use headers::components::ContentID;
 
 
 // TODO extend interface to allow some per mail specifics e.g. gen content id
 //      like `format!(_prefix_{}_{}, mail_cid_count, random)`
 //NOTE: Sized is just as long as Serialize is used for data
 pub trait Context: BuilderContext + Send + Sync {
-    fn new_content_id( &self ) -> Result<MessageID>;
+    fn new_content_id(&self) -> ContentID;
 }
 
 pub trait ContentIdGenComponent {
-    fn new_content_id( &self ) -> Result<MessageID>;
+    fn new_content_id(&self) -> ContentID;
 }
 
 #[derive(Debug, Clone)]
@@ -68,7 +67,7 @@ impl<I, B> Context for CompositeContext<I, B>
     where I: ContentIdGenComponent + Send + Sync + Clone + 'static,
           B: BuilderContext
 {
-    fn new_content_id( &self ) -> Result<MessageID> {
+    fn new_content_id( &self ) -> ContentID {
         self.id_gen.new_content_id()
     }
 }
@@ -76,7 +75,7 @