Hello,
all the blocked mails are sent directly from Google webmail to @gmail.com or other mailboxes hosted by Google. The mails are returned with:
550 5.7.1 [209.85.220.41 12] Gmail has detected that this message is likely unsolicited mail. To reduce the amount of spam sent to Gmail, this message has been blocked. For more information, go to https://support.google.com/mail/?p=UnsolicitedMessageError
On MS are mails moved to junk folder, others services like Yahoo, etc. are OKay.
DKIM, DMARC, SPF should be set up correctly. I've tested them (and also generated mails) on many platforms (G Workspace / Toolbox, MXToolbox, mail-tester.com, isux.com).
Moreover the same set up as we have now (Google Workspace & external mailing system) works within environments in another companies without any problem. I've also checked some RBLs and it looks like that one of Google IPs was/is listed on sorbs.net, which shouldn't be a problem I suppose (?)
Thank you in advance!
LinkedIn
Twitter
