Emails I send from my msn account to a group Gmail account keeps getting blocked and kicked back

Send the announcement in smaller batches rather than one 32-recipient Gmail-heavy message, and submit the complete bounce report to Outlook.com support if Gmail continues returning 550 5.7.1.

The evidence points to Gmail rejecting the bulk pattern, not to a general failure of the MSN mailbox: mail to other providers succeeds, and individual Gmail tests succeed. Google’s sender guidelines confirm that Gmail may block messages based on authentication, reputation, spam rate, and sending practices ^1^.

Immediate delivery workaround

1. Create a new copy of the announcement rather than repeatedly resending the same failed message.
2. Divide the Gmail recipients into smaller batches—for example, 5–10 recipients per message—and space the batches apart.
3. Put recipients in To or use separate messages rather than placing the entire group in BCC. Microsoft specifically recommends avoiding large simultaneous sends and not putting all recipients in BCC ^2^.
4. Remove unnecessary links, shortened URLs, repetitive promotional wording, and large attachments for the test.
5. Ask recipients who no longer want the announcement to be removed. Continue sending only to active recipients who read or reply.

Thirty-two recipients are below the documented maximum of 500 recipients per message for Microsoft 365 subscribers, although limits can vary by account history and are lower for non-subscribers ^3^. More importantly, an Outlook.com quota failure would not explain why only the Gmail copies are rejected with Gmail’s domain-reputation message.

About the matching Microsoft incident

Microsoft documented the same Gmail response—550 5.7.1 and “very low reputation of the sending domain”—for certain Outlook.com country domains and marks that incident as fixed. Its temporary workaround was to send through an @outlook.com alias ^4^.

That notice does not state that @msn.com is affected, so it does not establish that the old incident is the cause here. However, if smaller batches are impractical, an Outlook.com alias can be tested without creating a separate Microsoft account:

1. Sign in to the Microsoft account’s How you sign in page.
2. Select Add email.
3. Create a new Outlook.com address attached to the existing account.
4. Send one test announcement from that alias to a small Gmail batch.

The alias remains part of the same Microsoft account; adding it does not remove the MSN address ^5^.

Escalate persistent MSN-specific rejection

Because msn.com is Microsoft-managed, an individual user cannot change its SPF, DKIM, DMARC, outbound servers, or shared domain reputation. If both the small-batch test and Outlook.com-alias test produce different results, report that comparison to Outlook.com support:

1. Open Outlook.com in a browser.
2. Select Help on the menu bar and enter the delivery problem.
3. If self-help does not resolve it, scroll to Still need help? and select Yes ^6^.
4. Include:
   • The complete non-delivery report, including Gmail’s response and timestamp.
   • The fact that individual Gmail messages succeed.
   • The number of recipients in the failed message.
   • Whether smaller batches succeeded.
   • Whether the same message sent from an Outlook.com alias succeeded.
   • Message headers, with recipient addresses and other personal information removed.

Do not publish the complete bounce report publicly without removing email addresses, message IDs, IP details tied to the account, and other personal information.

References

1. Email sender guidelines - Gmail Help - Google Help
2. Sender Support in Outlook.com | Microsoft Support
3. Sending limits in Outlook.com | Microsoft Support
4. Fixes or workarounds for recent issues on Outlook.com | Microsoft Support
5. How to add an email address to your Microsoft account
6. Can't send or receive email in Outlook.com | Microsoft Support