IP Office Technical Tip (Region: Global)

133: SMTP Server Fails If Port 25 Is Blocked

13th March 2006 - Full PDF Text Version




The Voicemail and Conference Center Servers can be configured to send email alerts via SMTP. An SMTP Server or Service does however need to be installed and running on the Voicemail or Conference Center Server.


Attempting to establish a Telnet session to the SMTP Service on port 25 is unsuccessful:


The latest release of McAfee Anti Virus (8.0) includes a port block feature which, by default, blocks Port 25. Port 25 is the default port used for SMTP. The symptom of this issue is that Telnet sessions to the SMTP Server on Port 25 are unsuccessful. This may also affect other vendors’ anti-virus programs, however McAfee is the only one tested for the purpose of this Tech Tip.


When using McAfee Anti Virus, Open the Virus Scan Console, Open the Access Protection, Uncheck the Checkbox for "Prevent mass mailing worms from sending mail". You will notice the Ports reference is Port 25. You could also remove this option.

You should now be able to Telnet to the Voicemail Server.


If you choose to disable the "Prevent mass mailing worms from sending mail" Rule on the Access Protection Properties, you will want to explicitly allow access to minimize security risks. You can do this by restricting Security on the Voicemail SMTP Service, in the Internet Information Server Properties to only accept connections from the local PC, as no other systems should need access to this server to relay.