Mail Flow Rules Conflict: 50 MB Users Unable to Receive Emails When 100 MB Rule is Enabled

Question

I want to create a mail flow rule in Exchange 2019 to allow 50 MB and 100 MB email limits for specific users. The send/receive connector settings have already been configured, and I’ve created two separate rules—one for 50 MB users and another for 100 MB users. However, I’m facing an issue: users with the 100 MB limit can receive emails, but those with the 50 MB limit cannot. If I disable the 100 MB rule, the 50 MB users can receive emails. Both rules have the same settings and apply to different mailboxes, but I can’t figure out why only one rule works when both are enabled.

Answer 1

Hi, @Innocent Heartvoice

Thanks for posting your question in the Microsoft Q&A forum.

According to your description, you created two separate rules, but the user with the 100 MB limit can receive emails, while the one with the 50 MB limit cannot. If you disable the 100 MB rule, the 50 MB user can receive emails.

I want to confirm with you that your 100 MB rule has a higher priority than the 50 MB rule? You can determine the priority by querying the Priority of the rule with the command Get-TransportRule, where the highest priority value is 0.

If you want to set a 50 MB and 100 MB email limit for a specific user, you can try to achieve this effect through recipient restrictions. You can try to follow the steps below in EAC:

1. Set the size of incoming mail:
   • For mailboxes: Mailbox > Recipients > Edit > Mailbox Features > Mail Flow section > Mail Size Limits section > View Details > Received Mail section > Maximum Mail Size
   • For mail users: Recipients > Contacts > Edit > Mail Flow Settings > Mail Size Limits > View Details > Received Mail section > Maximum Mail Size
2. Set the size of outgoing mail:
   • For mailboxes: Mailbox > Recipients > Edit > Mailbox Features > Mail Flow section > Mail Size Limits section > View Details > Sent Mail section > Maximum Mail Size (KB)
   • For mail users: Recipients > Contacts > Edit > Mail Flow Settings > "Mail Size Limits" section > View Details > "Sent Mail" section > Maximum Mail Size (KB)

Refer to: https://learn.microsoft.com/en-us/exchange/policy-and-compliance/mail-flow-rules/mail-flow-rule-procedures?view=exchserver-2019#set-the-priority-of-mail-flow-rules

https://learn.microsoft.com/en-us/exchange/mail-flow/message-size-limits?view=exchserver-2019#recipient-limits

If you have any questions, please feel free to contact me. If the answer is helpful, please click "Accept Answer" because it can help other members of the Microsoft Q&A community who have encountered similar problems and are looking for solutions. Thank you.

Best,

Jeanne

Answer 2

Can you post the specific rules?

Also, keep in mind that the global transport send and receive limits should really match and there is an order of precedence on how limits are appliedhttps://learn.microsoft.com/en-us/exchange/mail-flow/message-size-limits?view=exchserver-2019