Ive seen this problem a few times, you are expecting an email but you never receive it and in event view you see the following error reported.
Source: MSExchange FrontEnd Transport
Date: 10/15/2015 12:26:10PM
Event ID: 2030
Task Category: SmtpSend
The Ehlo options for the client proxy target 192.168.1.2 did not match while setting up proxy for user domain/user on inbound session 08D084466731C660. The mismatched settings might cause some messages to get rejected. Continue with proxying even though there is a mismatch. The critical non-matching options were maxSize. The non-critical non-matching options were .
This error is seen if you have multiple Exchange 2013 or Exchange 2016 servers where the max receive size and transport size is mismatched across your servers on your receive connectors. We can resolve this issue by first finding our limits and setting them. This can be either done via the GUI – read this article or we can do it via powershell, read this article.
Get Exchange 2013 / 2016 Message Limits
First lets get the limits on each server:
get-transportconfig | ft maxsendsize, maxreceivesize get-receiveconnector | ft name, maxmessagesize
Once we have our limits on each server, compare them and find the limit what is restricting you. We can change the limits with the following powershell.
Set-TransportConfig -MaxSendSize 25MB -MaxReceiveSize 25MB get-sendconnector | set-sendconnector -maxmessagesize 25MB
Restart the Exchange Transport service and these settings will be immediately changed and active in your Exchange 2016 / 2013 org.
Tags: receive connector