Forum Discussion
Outlook emails to Gmail recipients: Get 421-4.7.28 temporary rate limit failure every other mailing
Hello. I am the volunteer IT director for my church. We send out periodic emails to our congregation with announcements from Microsoft 365 Business (Outlook), in which we have set up an email address...
Same issue here, I received this for just 21 bcc'd Gmail recipients! Which I have been doing for years as its to a social club.
Remote server returned '550 5.4.300 Message expired -> 421 4.7.28 Gmail has detected an unusual rate of mail originating from your DKIM;domain [MYDOMAIN.onmicrosoft.com 36]. To protect our users;from spam, mail sent from your domain has been temporarily rate;limited.
I'm in the same situation as you and have your exact issue. Did you get any resolution?