Currently, the only options for setting up Phorge to receive mail is to either use a mailing service like Mailgun, or have the mail server running on the same host as Phorge.
Neither of these really make sense for most setups, and Phorge already supports sending mail via SMTP - imo it would only make sense to support IMAP for receiving mail too.
Working around this right now by setting up a Relayed Domain on my mail server and pointing it to the server that my Phorge instance is running on. Obviously only an option if you are running your mailserver, and your configuration isn't too complex to support it.
If you're relying on a third party for your mail services, you may not have the option, so supporting IMAP is still necessary in most scenarios IMO.
I'm the author of this solution that works for me:
I don't have time to integrate myself in Phorge honestly. Having an external bot was fine for me.
Feel free to test/integrate or ask questions. The source code is available as FLOSS.