How can I send an email to multiple recipients (50+)

In Outlook for Windows (classic), messages to many recipients can be blocked by:

1. Recipient limits on the sending account (for example, some providers limit how many recipients can be on a single message or sent per day).
2. Server-side anti-spam rules that treat large recipient lists as suspicious.

To fix or work around this when sending to 50+ recipients:

1. Reduce recipients per message
   Split the list into smaller batches (for example, 10–20 recipients per email) and send multiple messages instead of one large one.
2. Use mail merge instead of a single bulk message
   In classic Outlook (not New Outlook), Word’s Mail Merge to Email feature sends one message per recipient, which avoids a single message with a very large To/CC list. If using New Outlook, switch back to Classic Outlook first, because New Outlook does not fully support mail merge to email and messages may not be sent at all.
3. Check whether New Outlook is in use
   If using New Outlook for Windows, bulk or mail-merged messages may appear to complete but never send. Switch back to Classic Outlook using the toggle at the top-right of the Outlook window (or under Help) and resend. Any messages queued while using New Outlook may be sitting in the classic Outlook Outbox and will send once classic Outlook is opened and online.
4. Contact the email provider or admin
   If messages are still blocked, the provider or admin may need to raise the per-message or per-day recipient limits, or confirm that the account is not being throttled as potential spam.

For future large sends (for example, newsletters), consider using a proper bulk-email or communication service that is designed for high recipient counts and includes throttling and delivery monitoring.

References:

• Mail merge to draft in outlook 365 - Microsoft Q&A
• Merge to Email problem - please help - Microsoft Q&A
• Mail Merge Emails not sent - Microsoft Q&A