550-5.7.1 [184.108.40.206 1] Our system has detected an unusual rate of
550-5.7.1 unsolicited mail originating from your IP address. To protect
550-5.7.1 users from spam, mail sent from your IP address has been
550-5.7.1 Please visit http://www.google.com/mail/help/bulk_mail.html to
review 550 5.7.1 our Bulk Email Senders Guidelines. e8si10598206wfd.104
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I don't have an open relay. I have SPF set up. I did have this postfix setting:
unknown_local_recipient_reject_code = 450
which I changed to:
unknown_local_recipient_reject_code = 550
So now it should reject while a server is trying to send email, instead of sending a bounce (backscatter), which might be what Gmail had a problem with.
I could try just using my ISP's SMTP server for outgoing email.
Any other ideas? Thanks.