Inconsistent Mail Sending Problems

[MasterChief]

Hello everyone, I've been researching for a week now and finally decided to just post my own thread here, since I've run into about 10 dead links trying to get it solved.

I rent a VPS from 1and1 Hosting, running Plesk 8.6.0. Ever since I bought it I have had problems sending email to certain people, at certain times. Unfortunately neither the people or the time bears any consistency, making it excessively hard to troubleshoot.

In this case, I've narrowed it to one troublesome person whom I do regular business with. His email is provided through yahoo.dk (he lives in Denmark, obviously) and no matter what I do, my mail to him gets stuck in the remote queue.

This problem goes in and out over time. I've never (to my knowledge) had trouble receiving mail from him, only sending it to him.

I've also noticed a large number of emails from yahoo.tw and other odd domains I don't know piling up in my remote queue as well. I'm thinking a spammer is using my email server to bounce his junk, and as such the yahoo.dk server is occasionally blacklisting me for a time.

I'd greatly appreciate any help anyone can offer me. I've been bashing my head against a wall over this for the better part of 4 months, and it's put a lot of strain on an otherwise good professional relationship.

Thanks in advance,

~Michael

 

[Faris Raouf]

If what you think is happening is the actual reason for the problem (and it seems reasonable) then there's nothing you can do other than to contact yahoo.dk's postmaster helpdesk (if such a thing exists).

But what is the error in the maillog that you see when your server tries to send to yahoo? Normally the reject reason will be shown, sometimes incorporating a link to a url providing more info.