I suggest to implement the following feature:
Allow saving of e-mail (sometimes known as EML file) instead sending e-mail via MailJob-provider.
A typical use case might be:
a) From time to time I need to look at the e-mail which is generated by using the LL-MailJob-provider. So I first need to send it, so that I can look afterwards, if the message is as expected.
b) I can create draft-messages and save them on disk and send them later. Well, it would be kind, if you could support loading an EML-saved message and sending it via LL-MailJob-provider. Otherwise d)
c) As you are not willing to implement this suggestion: Additionaly allow to save e-mails in Sent folder, I could use method b) to do it myself
d) I can use curl to send e-mails.