Help Needed with SBS2003 and DynDNS

[Seg2011]

Hi guys.

I really need some help with setting exchange up with DynDNS.

I am running my server on a Dynamic I.P and using DynDNS updater to track IP changes, and everything is fine on that end. Now to the tricky bit. I have a domain

http://www.mydomain.co.uk

and a DynDNS domain mydomain.mydomain.net,

http://www.mydomain.co.uk

is forwarded to mydomain.mydomain.net. When I use network tools to check email validation, I get the following: Validation results
error: Recipient rejected

canonical address: <seg@sy-net.co.uk>

MX records



preference

exchange

IP address (if included)



5

mail.sy-net.co.uk

[66.98.136.44]



10

mail.synet.selfip.net.sy-net.co.uk

[66.98.136.44]

SMTP session
[Contacting mail.sy-net.co.uk [66.98.136.44]...]
[Connected]
220 microlite1.com ESMTP Sendmail 8.12.10/8.12.10; Sun, 29 May 2011 10:24:26 +0100
EHLO Network-Tools.com
250-microlite1.com Hello 67.222.132.193.tailormadeservers.com [67.222.132.193] (may be forged), pleased to meet you
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-8BITMIME
250-SIZE
250-DSN
250-ETRN
250-AUTH GSSAPI DIGEST-MD5 CRAM-MD5
250-DELIVERBY
250 HELP
VRFY seg
252 2.5.2 Cannot VRFY user; try RCPT to attempt delivery (or try finger)
RSET
250 2.0.0 Reset state
EXPN seg
502 5.7.0 Sorry, we do not allow this operation
RSET
250 2.0.0 Reset state
MAIL FROM:<admin@Network-Tools.com>
250 2.1.0 <admin@Network-Tools.com>... Sender ok
RCPT TO:<seg@sy-net.co.uk>
550 5.7.1 <seg@sy-net.co.uk>... Relaying denied. IP name possibly forged [67.222.132.193]
[Address has been rejected]
RSET
250 2.0.0 Reset state
QUIT
221 2.0.0 microlite1.com closing connection
[Connection closed]

Can anyone give me a guide to setting up exchange with DynDNS, as everything I have read on the tinterweb either doesnt work or isn't very clear.