Cannot receive emails from gmail - exchange 2003

Hi all.
I have in my company a exchange 2003 server running on Windows server 2003 sp2.
I recently moved our the DNS and MX records to our domain provider (123-reg) as this was all open recursive DNS on our own servers.
123-reg have confirmed i've copied everything over correctly a couple of days ago.
Since making the change. Gmail users cannot email our domain. We can successfully email gmail accounts though. (and all other emails inbound and outbound seem to be working fine)
After checking the SMTP logs, I can see that the mails are getting to the server, but they are not arriving in users mailboxes.

I have GFI mailsecurity installed. I cannot get into this as i don't have a password (awful handover!). I have tried disabling GFI services but that doesn't make the mails appear either. I've never used GFI, so if anyone has ideas here, that would be helpful.
Thanks very much for reading.
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Thomas GrassiSystems AdministratorCommented:
Simon Butler (Sembee)ConsultantCommented:
GFI usually uses AD credentials. Therefore if you have the domain admin account, then try using that to login.
I would also query Message Tracking to see what Exchange is doing with the email. If you stopped the GFI service, then the email should have gone through - therefore it has to be something else.

jamiegfAuthor Commented:
Hi Thomas. I seem to have lots of entries like this:

2011-07-22,12:47:06,108,3,"#00001a50","#000005bc","info   ","ase_ipwhitelist",">> Init Message [<>]"

Id there anything i can do here to allow all in?
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jamiegfAuthor Commented:
Thanks Simon. I'm still trying to find an account that works here :(
Thomas GrassiSystems AdministratorCommented:
Have you checked your exchange server settings

Been a long time since I used 2003  but if I remember correctly look at this

In Exchange System Manager, Message Delivery,  Sender Filtering tab.

Do you see any entries in there?

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jamiegfAuthor Commented:
Hi Thomas. Thanks, Ive had a look at the filtering tab.  It is definitely something to do with Intelligent Message Filtering.

If i send a test mail over 3MB, the mail gets delivered, and I get an event in the eventlog saying "An error occurred while Microsoft Exchange Intelligent  Message Filter attempted to filter a message with ID......"

If i send one less than 3MB, then it doesnt reach the recipient. After a bit of googling I can see this is by design as most spam mail was less than 3MB.
 I just cannot see any rules that block out
jamiegfAuthor Commented:
I figured it out eventually. It was the Intelligent Message Filtering tab. Turning up the SCL thresholds fixed issue.
Thanks Thomas, for pointing me in right direction.
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