How to get to know why exactly our emails are getting blocked by Google

[hvysocina]

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!

[hvysocina]

Hello, it's fixed. Problem was because of mailing list provider. I recommend to use more DNS/SPF checkers (not only MXtoolbox, G tools).

[kamalziba]

Our academic organization has a similar problem and it has wasted a lot of my time. If the Gmail admin sees this message, please fix the problem. We have no way to send to other domains and we are not on any block list.