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Unable to telnet to destination

Last Modified: 2013-11-30
Experts this is actually a Exchange related question, but I suspect it will best be answered here.

I am attempting to telnet to a mail server located at  The connection is either accepted or not accepted.   I have no affliation with the destination email server, all that I do know is that 2 of 3 unrelated sites I maintain cannot send email successfully to it.

So far I have not been able to precisely narrow down the root cause of why the connection is not accepted.  

I have been able to eliminate an ISP/ route  issue (I can connect from certain machines; the issue spans 3 different ISPs)
I think I have been able to eliminate telnet protocol issues (I can connect from one exchange 2007 SP2, but not another)

I have also tried different ISPs, and different networks with mixed results.
examples:(for testing purposes I have set my global outs the same for each test)

If it helps he 3 sites share a commonality in Firewall and antivirus products.

Site A/ ISP A
Server A: WinSBS2008- No success  (exchange)
Server B Win2003 standard- Success
Server C: Win2003 standard- Success

Site B/ ISP A
ServerA: WinSBS2008- Success  (exchange)
ServerB: Win2003 standard- Success

Site C/ ISP B
ServerA: Win2008/Exchange2007- No Success
WorkstationA: Windows 7- No Success
ServerB: Windows 2003 standard- Success

Any help appreciated

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