maximum limit max recipients how many emails recipient limit sending limit campaign size
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What are the maximum limits for mail merge campaigns?

Learn about the recipient limits and sending constraints for SecureMailMerge campaigns.

Contents

SecureMailMerge does not impose any artificial limits on the number of recipients you can include in a mail merge campaign. However, there are some practical considerations:

Microsoft 365 Sending Limits

Your sending limits are determined by your Microsoft 365 subscription and tenant configuration:

  • Microsoft 365 Business: Typically 10,000 recipients per day
  • Exchange Online: Usually 10,000 recipients per day with a maximum of 500 recipients per message

These limits are enforced by Microsoft, not SecureMailMerge. Your IT administrator may be able to adjust some of these limits for your organization - contact them if you need higher limits.

Attachment Size Limits

The default message size limit in Microsoft 365 is 35 MB (including attachments). Administrators can increase this up to 150 MB. Keep in mind that attachments grow by about a third when sent via email, so a 24 MB file actually uses around 32 MB of your limit.

For large files, consider sharing via OneDrive or SharePoint links instead of direct attachments.