Make GreenMail configurable - how to provide own Managers

[shadogray]

I would like to provide own Managers, ServerSetups and Commands.
It seems to be not possible now, why are so many components private or static final?

[marcelmay]

It's pretty old software (before 2006), but we can improve it :-)

Out of curiosity: What is the motivation to replace those central components with own implementations? So that we can change it for the better.

[marcelmay]

What about something like this:

Managers:

• Additional, optional com.icegreen.greenmail.util.GreenMail constructor
  GreenMail(ServerSetup[] config, Managers managers)

Commands:

• Allow eg com.icegreen.greenmail.smtp.commands.SmtpCommandRegistry to add/override commands:
  void setCommand(String name, SmtpCommand command)

Looking forward to your feedback

[shadogray]

Reasons for change:

• Mailserver validation: we implemented it in our MailCommand, but everything had to be copy/pasted, because: final static, no inheritance, no stack builders, private business logic
• UserManager proprietary - you frequently want some domain specific logic regarding valid/SPAM mail
• to me a question of usability: customizable (error) messages, that allow quick and unexpensive understanding of the problem. This is a difficult topic regarding security (by obscurity?), but it simply may help to understand, as in RFC1893, and I am tired of answering silly/repetitive questions, because response is (unnecessarily) unclear.
  I am not an SMTP (simple?) expert, I see an incredible potential in GreenMail, but I need domain specific logic and I loath copy/paste. I did it now twice and I am sick of my hacks.

[kimmerin]

Out of curiosity: What is the motivation to replace those central components with own implementations? So that we can change it for the better.

Old thread but still open, so here are my 2 cents: E.g. "override" the IMAP Authenticate command that currently only returns an error to allow the testing of XOauth2 authentication. That's why I wanted to open an issue here before finding this one that already fits in a way.

[marcelmay]

@kimmerin , a concise PR for XOauth2 would be quite welcomed.