Question : telnet exchange5.5 @25

can we verify a user at port 25 on exchange.
Example:
telnet exchange 25
vrfy user1
250com>

Answer : telnet exchange5.5 @25

repost of answer:

For security reasons, VRFY is disabled by default. But it can be enabled by doing the following;
 
 1. Open Regedit.exe
 2. Open the following registry keys:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\
MSExchangeIMC\Parameters
 3. Choose Edit, and choose New DWORD Value.
 4. Type EnableVRFY; under Value data, type 1.