The following error may be visible in the logs relating to an external sender who is unable to send an email to InterScan Messaging Security Virtual Appliance (IMSVA).
#5.0.0 SMTP; 544 Transaction failed
The issue happens because the sender's IP address is listed on Trend Micro Real-Time Blackhole List (RBL), hence the email is rejected by the Email Reputation Services (ERS). IMSVA uses ERS to determine safe sending IP addresses.
To verify, check the sender's MTA IP address and go to https://www.ers.trendmicro.com/reputations/index to see if it is listed in any Trend Micro RBL.
If it is not listed on ERS, check if the IP address is listed locally on IMSVA, under Sender Filtering > Blocked List or Suspicious IP.
To resolve the issue, do any of the following:
- Option A. Send a request to remove the valid IP address from the ERS database.
- Option B. Add the IP address in the Approved List to bypass ERS checking.
- On the IMSVA console, go to Sender Filtering > Approved List.
- Click Add.
- Enter the IP address or IP address ranges you would like to allow.
The relevant IMSVA logs related to this can be viewed under Logs > Log Query > Sender Filtering.
For more details on Email Reputation Services, please refer to IMSVA Administrator's Guide Page 39.