[Typo3] DMail 1.0.3 + upgraded-typo3 problems

[Jerker (Eric) Helander]

Dear All,

I had a Typo3 3.5 installation on server A. It was working fine and the 
dmail mailinglist plugin sent out my newsletters as intended.

For various reasons I had to move the installation to server B, at the same 
time I upgraded it to 3.8. Everything works fine now, except that 
newsletters are not sent to "external" email addresses.

Server B is the nameserver and email host (pop3) for 20+ domains. If I try 
to send a newsletter to an email address which IS hosted on server B it 
works, but if I send a newsletter to e.g. x at hotmail.com the newsletter never 
arrives.

I get no error messages whatsoever.

I've tried to send test emails (both with and without HTML) to my 
hotmail/yahoo addies in the install-tool email test, and they DO arrive.

Any ideas?

Thanks in advance for your help

/Eric