unable to send emails to a group of people

bill jones 0 Reputation points
2026-09-12T17:31:56.8333333+00:00

I have been trying to send minutes of a meeting to twelve people and i keep getting message from postmaster general saying that they have failed to be delivered

Outlook | Web | Outlook.com | Email
0 comments

1 answer

Sort by: Oldest
Most helpful Newest Oldest

  1. AI answer

    2026-09-12T17:32:12.54+00:00

    Check the non-delivery report from the postmaster and look for the "Diagnostic information for administrators" section. That section usually states why delivery failed.

    For a message sent to 12 people, the most likely fixes supported here are:

    1. Verify each recipient address
      • Open the message again.
      • In the To box, delete each recipient address that may be wrong.
      • Start typing the address and, if it appears in Auto-Complete, remove the old suggestion.
      • Re-enter the full address carefully and send again.
      • This helps if one or more saved addresses are outdated or misspelled.
    2. Reduce recipients and test in smaller batches
      • Try sending to 1 to 3 recipients first.
      • If that works, send the remaining recipients in smaller groups.
      • This can help if the send attempt triggered anti-spam protection.
    3. Check attachment size
      • If the meeting minutes include an attachment, Outlook.com cannot send the message if an attachment is larger than 25 MB.
      • Some failed delivery guidance also notes problems when the original message had an attachment larger than 10 MB.
      • If the file is large, upload it to OneDrive and send a link instead.
    4. If the error mentions mailbox full
      • The recipient’s mailbox cannot accept new mail.
      • The message can still be delivered to other recipients.
    5. If the error mentions server timeout, connection timed out, or message expired
      • Wait a short time and resend.
      • These errors often resolve on their own.
    6. If the error mentions blocked, blacklist, spamcop, dynablock, blackhole, or spamhaus
      • The recipient’s mail server blocked the message as suspected spam.
      • The recipient’s email provider support team must unblock the account or domain.
    7. If sending from Outlook or another mail app
      • Try sending the same message directly from Outlook.com.

    If the addresses are correct and the message still fails, check whether the message has a signature and try removing it before resending.

    AI-generated content may be incorrect. Read our transparency notes for more information.

    Was this answer helpful?

Your answer

Answers can be marked as 'Accepted' by the question author and 'Recommended' by moderators, which helps users know the answer solved the author's problem.