Add possibility for naming on Attachments

[Lejla94]

Currently the attachments (my case inline) are named after the content type. Is there a way to change that name?

If not, can this be implemented?.

[paolobarbolini]

We don't currently have an easy API for that, but if you'd like to send a PR for it I'd be more than happy to review it. Here's where the Attachment code lives https://github.com/lettre/lettre/blob/master/src/message/attachment.rs

(guessing on your code from https://github.com/image-rs/image/issues/1629, if I hadn't seen it first I couldn't guess you're using Attachment :smiley:)

[Lejla94]

oh sorry, for not mentioning that i used Attachment. I am coming from javascript world, so it will need some time to become familiar here!