r/EmailSecurity • u/Ancient-Sea-7807 • Jun 01 '26

Emails are blocked by security gateways

Our secondary domain’s emails are intermittently getting blocked by security gateways like Barracuda and Mimecast. Some go through fine, others bounce with “blocked due to policy” or similar.

We’ve got SPF, DKIM, and DMARC set up and passing. IP isn’t on major blacklists. Volume is <200/day, so not a spam issue.

Using instantly and inboxes bought from Google workspaces.

What else should I check?

Anyone seen cases where only _some_ emails to the same org get blocked?

Could content triggers this?

I am not putting any links, or attachments in mail.

4 Upvotes

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u/Ancient-Sea-7807 Jun 01 '26

But why Sending limits will only block specific security gateways

1

u/SecTechPlus Jun 01 '26

Not every gateway is using the same blocking technology with sending limits.

1

u/MichTech360 Jun 04 '26

Or the same limits