Streaming attachments about play-mailer

[mkurz]

With play-mailers own Email class, currently this is not possible (yet). Right now we support only files or arrays as attachment.
However, play-mailer uses Apache Commons Email under the hood, which provides some additional methods to attach(...) attachments, like passing a javax.activation.DataSource...
You are welcome to provide a pull request... You would need to add another method to handle a Source[ByteString, NotUsed] and convert it to a DataSource, similarly to these methods.

Actually looking at the code it looks like there is a workaound for now... The MailerClient you inject is an object of CommonsMailer, therefore you could use the the ´createEmail(...) method which gives you a Apache Commons MultiPartEmail which you can then send, like

val multipartEmail = commonsMailerClient.createEmail(myExistingEmail);
multipartEmail.attach(myDataSource, ...); // multipartEmail is Apaches own email implementation
....
commonsMailerClient.send(multipartEmail);

[tg44]

The project currently not use any akka deps, this was the main reason I didn't hop to a "lets make a PR" train.

What do you think, should we document this workaround, or create a module/artifact just for the additional streaming? Adding akka as a dep could be a pain, I would not cross that bridge if I don't need to...

[mkurz]

Finally found time for a PR: #193