After looking into the problem, we confirmed that all of our receive connectors accepted a large file size of 30mb. So that didn't seem to be the cause.
Well we found the cause of the problem seemed to be because of the max header size setting on the receive connector. Here is what we changed.
- Open up Exchange Management Console
- Enter Get-receiveconnector
- This will show a list of all of your receive connectors
- Enter get-receiveconnector -identity "name of connector" | fl to see all of the connectors settings
- To modify the connectors settings enter Set-receiveconnector –identity “name of connector” -MaxHeaderSize 256kb
It may take up to two hours to update the Exchange cache settings.
After we applied this setting, the email came in successfully on testing.
Did this guide help you. We'd like to know. Let us know your thoughts in the comments section below.