I did run some packet captures today and it appears that the receiving server for my outgoing messages is sending the timeout to my server.

I’ll start trying to develop some good Google searches to see what I can come up with to resolve this issue and make my server react faster in response.

I am sure that the SMTP is coming from the Exchange server public IP address. Checking test mails sent to the few domains I am actually able to get mail through to, the headers show the correct from IP address and checking with several of the online testers shows the correct IP.

I’ve downloaded both of the programs you mentioned, and will log into the server first chance and give them a whirl.

I do appreciate your help.

To Technochic: the problem was not with DNS, but with the PTR record, which is commonly called rDNS, or reverse DNS. The problem is that I need to rely on Verizon for that record as they normally advertise it as something else. That has been fixed.

It could also be that the telnet session is being sensed by the remote server as being run by a human, so command timing could be a problem. Consider using some type of SMTP client which can generate the commands faster than a human can type. I have an old application called Genius 3.2.2 that I use for this purpose but I cannot find it on the internet any more and the locations where it looked like it may be available are of questionable integrity. I did find another tool called SMTPTools at Tucows that might fit the bill for this purpose. I tested Popcorn from Ultrafunk (now defunct <g>) and it seems to do the trick for quickly sending messages using SMTP.

Neither of these tools require installation and can be used from client or server. Hopefully this will help you track down the issue.

RCPT TO: with the address is posted, no reply from the receiving server.

Firewall has been checked and refreshed.