Hello,
I'm at my wits end trying to figure out why my on-premise Exchange 2013 server is rejecting emails, claiming that they're too large. The rejection message was:
[(MyIPAddress)] reply 552 5.3.4 Message size exceeds fixed maximum message size
I have read numerous articles online regarding max attachment and message sizes, and everything seems to be OK. For context, what I want to occur is messages greater than 30 MB are rejected, but anything smaller is OK. I am getting rejection messages on an email from outside the organization with an attachment that is only 24 MB, and nothing else other than brief text in the email body.
I've run the four commands from this article:
https://www.codetwo.com/admins-blog/exchange-attachment-size-limit-find-change/
get-transportconfig | ft maxsendsize, maxreceivesize get-receiveconnector | ft name, maxmessagesize get-sendconnector | ft name, maxmessagesize get-mailbox Administrator |ft Name, Maxsendsize, maxreceivesize
and they all return back values of 30 mb max (or unlimited for the Admin box), which is fine and expected.
I have gone to Mail Flow > Receive Connectors, and verified that every connector has a 30 MB max value. I have gone to Organization Transport Settings window, and have verified that the Maximum receive Message size is 30 MB. I have gone to Mail Flow > Rules, where I have a rule that checks if "Any Attachment is greater than or equal to 30 MB" reject the message, and a rule that checks if "The message size is greater than or equal to 30 MB" to reject the message. There are no other rules.
I don't know if there are commands that can help check attachment size settings, but given the rejection message I mentioned at the beginining, it sounds like a message size rule.
I have run the get-transportconfig | fl command, and I don't see anything out of the ordinary from the results except potentially this value:
ExternalDsnMaxMessageAttachSize is 10 MB
but, from my limited understanding from googling, it sounds like the DSN messages are the delivery notification messages, and therefore this value should not apply to as a max message size value for normal emails from clients for example, correct?
Anyone able to think of anything I may be missing?