Exchange does not accept emails larger than 10 MB — how to increase the limit

Exchange receive connectors have a default maximum message size of 10 MB (10240 KB). Increase this as follows:

Exchange Management Console (2007 / 2010)

1. Go to Server Configuration > Hub Transport > Receive Connectors.
2. Open the default receive connector.
3. On the General tab, increase Maximum message size from 10240 KB to your desired limit (e.g. 102400 for 100 MB).

Exchange Management Shell

set-receiveconnector "*default*" -maxmessagesize 100MB

You may also need to increase the limit at the organization level: Organization Configuration > Hub Transport > Global Settings > Transport Settings.

The limits of current Exchange versions (2016, 2019, SE) with Microsoft's default values, and what happens to a message at each of them, are in the guide Messages over 10 MB are not arriving: size limits between the POP3 connector and Exchange.

Screenshots — step by step