Troubleshooting: 500 Line too long

Q:

subject: Delivery Final Failure Notice

Can not deliver the message you sent. Will not retry.

Sender: <[email protected]>

The following addresses had delivery problems

<[email protected]> Reply from mail.xxxx.yyy.com[xxx.xx.xx.xx]: 500 Line too long

<[email protected]> Reply from mail.xxx.yyy.com[xxx.xx.xx.xx]: 500 Line too long

<[email protected]> Reply from mail.xxx.yyy.com[xx.xx.xx.xx]: 500 Line too long

A:

The message was coming from the SMTP proxy service on the firewall. The proxy service has a setting that controls the maximum line length. This was set to 1000. To fix it I increased the limit to the one you said was imposed by Exchange of 8,000, resent my test email and it went through just fine. Just an FYI-for some reason most of the emails I was notified of came from the xxx.com domain. To fix (I have the Watchguard Firebox X Edge X20e)

1. Firewall > Incoming > SMTP Proxy

2. Click Edit

3. Click the SMTP Settings Tab

4. Change Maximum Line Length