[feat]: SMTP server

[ProofOfKeags]

• [ ] PGP email encryptions
• [ ] Do we need STARTTLS to get past spam filters
• [ ] Define and exclude sensitive information from the emails
• [ ] Communicate any privacy weakening that happens as a result of enabling this feature

[MattDHill]

This is not just an extension of the notification system. EOS should be able to send emails without issuing a notification. An example of this would be a service wanting to send a verification email.

[elvece]

See https://github.com/Start9Labs/embassy-os/issues/1783