Mail server rejecting POP3 requests outside firewall

[Rainman]

I'm have a problem with our university's mail server rejecting some of the users who are trying to check their email from home. In particular this is the case with AT&T broadband, as the other ISP's some of the users use are fine. Do you have any suggestions as to what might be the matter? I can post a copy of the log when we try to query the server.

Any help would be greatly appreciated.

 

[Scarpozzi]

How long has your pop server's host name been registered with your registrar? Most of these problems (when some can hit it and others can't) are simply DNS issues if the host name isn't recorded properly on the DNS server of the ISP. I would do a test with a user that's called and see if you can get them to manually change their DNS settings to the University's DNS server. This is all to troubleshoot the problem, for a quicker test, of course you can have them type in the ip of your pop3 server in their mail settings rather than typing the pop3 host name. Good luck and let us know if this doesn't take care of it! Cheers!

 

[n0cmonkey]

What mail server are you using?

 

[FUBAR]

It may be possible that your server by default only allows it's own subnet in, along with that it may be the case that at some point other ISP's subnets were allowed in. What do you see in your logs when these users fail?

 

[dbx]

My old @home mail server wouldn't let me check from anything other than my @home subnet address. But he said that some users can use the server fine from other isp. Only thing I can think of is maybe somewhere along the line, access has been denied (maybe not specificly) to those subnets that are having problems.

 

[Rainman]

Thanks for the suggestions guys. Our university's IT dept manages the email servers and unfortuately they aren't the most competent people and as a result I don't have access to the servers. I'm just trying to see what could be the cause of the problem and suggest a solution to our IT dept.