I know, it is common stuff but for someone it could be helpful.
We can use generic test for unsolicited bulk email (GTUBE) and send message with the following string:
Basically the GTUBE is supported by many anti-spam solutions (except WatchGuard) such as:
- Cisco Ironport
- Microsoft Forefront Protection for Exchange
The error that the other server returned was: 550 5.7.1 Message rejected due to content restrictions
- Commodo Antispam Gateway
Action: failed Status: 5.5.0 Diagnostic-Code: smtp;550 GTUBE found in message. See http://spamassassin.apache.org/gtube/
Similar way can be used also for a malware test message (EICAR test file):
Enjoy testing ;).