> The ISP is a University system that we send a lot of mail to.

What server???  I could try from my side if I knew what server you are talking about.  Please do not make us guess about the problem.

> I had turned session logging on for a bit and didn't see anything that stood out and basically the same as the MercuryE module window.

Could you post the session log?

> I did increase my timeout setting but that didn't seem to improve
> things.

To what?

> I don't have trouble sending mail to other domains and according to one of their email admins they have 25 inbound smtp servers.

No big deal, a lot of places have multiple mail servers.

> I just thought it was odd that MercuryE only seems to try 4 before it stops and puts the message back in queue.

I doubt it unless the first 4 servers in the list are bogus and are there to stop spammers.  What happens when you telnet in port 25 of these hosts?

I am currently using MercuryE and while it seems to work fine I seem to have trouble with delivering mail to one ISP who has approxiamtely 25 inbound SMTP servers. When I see MercuryE connect to it when they are very busy I can see it trying to connect to the alernates to try and find an available one. The problem I ma seeing is that MercuryE will only try (4) servers total and then pulls the message back into the queue. Is there a way to increase the amount of servers it will try when trying to make an SMTP connection?

Thanks,

Karl

> I am currently using MercuryE and while it seems to work fine I seem to have trouble with delivering mail to one ISP who has approximately
> 25 inbound SMTP servers. When I see MercuryE connect to it when they are very busy I can see it trying to connect to the alternates to try
> and find an available one. The problem I ma seeing is that MercuryE will only try (4) servers total and then pulls the message back into
> the queue. Is there a way to increase the amount of servers it will try when trying to make an SMTP connection?

No there is not but this is really strange, what timeout setting are you using?  With MercuryE I always set this to 300 seconds and I've not really had a problem delivering to any mail server.

One thing to check though, you should turn on session logging and check the actual connection to this host.  This host may be rejecting the connection from your system. especially if the IP address happens to lie within your ISP's randomly assigned IP addresses or the rDNS returns something other that the connecting host name.

 FWIW, what ISP is doing the blocking??

The ISP is a University system that we send a lot of mail to. I had turned session logging on for a bit and didn't see anything that stood out and basically the same as the MercuryE module window. I did increase my timeout setting but that didn't seem to improve things. I don't have trouble sending mail to other domains and accroding to one of their email admins they have 25 inbound smtp servers. I just thought  it was odd that MercuryE only seems to try 4 before it stops and puts the message back in queue.