Add ability to customize the Content-Transfer-Encoding header

[stalwartlabs]

Add ability to customize the Content-Transfer-Encoding header

[mdecimus]

Great, I'll do a few tests and publish the new version to crates.io next week.

[mdecimus]

@soywod I tested the new version and it looks fine, so I've just published mail-builder 0.3 on crates.io.

[mdecimus]

Please check the new version I've just committed to this repo. It is now much simpler and less confusing to add message parts.
With the new version make sure you pass the pgp-encrypted contents as a string so they are not base64 encoded:

Multipart::new("application/pgp-encrypted", "Version:1 \r\n");

[soywod]

It works way better, and the API is indeed simpler to use. Thank you!

[soywod]

Let me know whenever you publish the new version, I am waiting for it to release new version from my side 🙂 (it looks like you cannot publish crate with git deps, they all need to have fixed versions 🤔).