docker-simple-mail-forwarder
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Support for ARC
Can we please support the ARC protocol? It will reduce the likelihood that the forwarded email goes into spam.
https://support.google.com/a/answer/13198639?sjid=16402237990595946972-NA https://datatracker.ietf.org/doc/rfc8617/
I’d love to review a PR for that!
For example, if the source domain does not have a DKIM record but has a SPF record, the mail will not go through.
postfix/smtp[12529]: EF7A17EBEE: to=<[email protected]>, orig_to=<[email protected]>, relay=gmail-smtp-in.l.google.com[74.125.142.27]:25, delay=3.4, delays=2.9/0/0.1/0.45, dsn=5.7.26, status=bounced (host gmail-smtp-in.l.google.com[74.125.142.27] said: 550-5.7.26 The MAIL FROM domain [source.domain] has an SPF record with a 550-5.7.26 hard fail policy (-all) but it fails to pass SPF checks with the ip: 550-5.7.26 [docker.ip]. To best protect our users from spam and phishing, 550-5.7.26 the message has been blocked. Please visit 550-5.7.26 https://support.google.com/mail/answer/81126#authentication for more 550 5.7.26 information. - gsmtp (in reply to end of DATA command))
Also the bounced email generated sending back to source email does not appear to use DKIM authentication itself either, causing further DKIM failures.