Qmail queue help

[Karabaja]

Just moved to new host. And this issue wasn't present at old one. Not sure what changed. We use vps hosting. And we have vbulletin board installed on it. From time to time we need to send mass email to about 2500 members atm. It was not an issue on old server. But now when I sent this mass email people reported they didn't get it. I checked plesk mail tab. And it had a lot of queued mails.
I have this in plesk for those emails:
Received: (qmail 16058 invoked by uid 48)

There is a difference between old server in Plesk. We have plesk 8 on this one. But I don't think that should have an effect.

I read on plesk site that this qmail message probably means that some php script is trying to send spam. And that php script in this case is vbulletin board and it is not trying to send spam.
How can I fix that and avoid emails from vbulletin board being queued. I don't really have much experience in all this.
And why are all this messages marked as remote?
Which ones are local then?

[Karabaja]

I just noticed something. On old server there is mydomain.com in file called "me" in /var/qmail/control
on new server I have vps.mydomain.com
Should I change that?