I have a dedicated 1and1 box. I was using their DNS and email servers to run my site. I'm in the process of moving all of that now. I have other domains working of DNS and it works great. One problem with mail though. I am not able to send out from it.
I get the famous
'Sorry, that domain isn't in my list of allowed rcpthosts' and can't send mail.
I have checked my rcpthosts file and all the domains on the box are listed in the file, which 'should' fix the program. No go.
