Bulk sending of 50 emails

Ian Grinstead 0 Reputation points
2026-10-03T13:30:20.62+00:00

Hi,

I present a radio show which for the past 5years has had a link sent out via Outlook/ntlworld email.

I have regularly sending 50 emails with a link to my Dropbox and we transfer so the show can be downloaded and used.

However since coming back from holiday at the beginning of September i cant send bulk emails via bcc or using mail merge, mail merge sent 17 emails this morning then stopped sending the rest and bcc just a no go, if I send an individual to someone email its fine.

I have deleted the outlook account and reconnected via imap as per instructions and yet still the same issue.

If I send bulk emails using just the ntlworld Web email then it works and sends to all but when using new outlook it fails.

So my question is, is this Microsoft/outlook triggering a spam send(although its not) and blocking sending emails.

I have read the outlook has tightened up on bulk sending of emails recently and wondering if this is the case.

I am running windows 11 fully updated and using new outlook.

Any help would be appreciated.

Outlook | Windows | New Outlook for Windows | For home
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  1. Chloe-V 13,460 Reputation points Microsoft External Staff Moderator
    2026-10-04T02:14:53.2266667+00:00

    Hi @Ian Grinstead

    I understand how frustrating this is, especially since the same mailing method worked successfully for several years.

    Since individual emails work and all 50 messages can still be sent through NTLworld webmail, your account does not appear to be completely blocked. The issue may instead be related to how New Outlook handles bulk sending through the NTLworld IMAP/SMTP connection.

    Please try sending the messages in smaller groups of 10 to 15 recipients, with a short interval between each group. When Mail Merge stops, check the Outbox, Drafts, and Sent folders for any pending messages or sending errors.

    If Classic Outlook is available, please test the same mailing there. If it works correctly, this would help determine whether the behavior is specific to New Outlook.

    For now, you can continue using NTLworld webmail as a temporary workaround, since it successfully sends the full batch. Please let us know if any error message or code appears when the remaining emails stop sending.

    If the answer is helpful, please click "Yes". If you have extra questions about this answer, please click "Comment".   

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