Exchange 2010 SMTP timeout

Hi, I am getting a long SMTP transaction time (45 seconds) connecting to our Exchange 2010 server from the internet. Our voice mail server (not on our network) times out trying to email to our Exchange 2010 server.  The funny thing is that most senders do not have problems sending to us, and when I send mail from my gmail account, it is received in about 10 seconds.

I have disabled tarpitting (which was only 5 seconds) and disabled all message filtering.  This did not change the SMTP transaction time.

I have two receive connectors:
DEFAULT RELAY, Network config to receive email from remote servers on our local subnets (exchange 2010 would not let me leave this blank).  Available security: TLS, basic auth, exchange server auth, and integrated windows auth. Permission groups, anonymous users.
OUTSIDE RELAY, network config to receive from, same auth minus exchange server, Permission groups, anonymous users.

When I telnet in, after the 45 second delay, I get the default relay connector instead of the outside relay.

The path received mail takes from the internet is 1) Windows 2008 R2 firewall/vpn server, deep six spam box, and then the exchange server.  The voice mail server is on the same subnet as the internet facing address of the firewall server.

Any suggestions on fixing this?  Thanks in advance for your help.
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RadweldConnect With a Mentor Commented:
I would be looking at your deep six spam box for answers. You could configure your firewall forwarder to target the Exchange 2010 Hub transport directly in order to test this. if all of a sudden your connection times speed up you know there is an issue with that appliance. I would also consider reconfiguring your relays,
StolzmanAuthor Commented:
Yup, that was it, the spam box was causing the delay.  I've got a help ticket in with the mfg.  Thanks.
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