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Outbound email works, but inbound email is not going through.

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May 15, 2007
7
US
I'm having an issue with inbound email flow to my organization. Emails work fine outbound no problem, but emails inbound seem to be getting delayed from external email addresses, such as yahoo and hotmail.

This is the error message from hotmail.

This is an automatically generated Delivery Status Notification.
Unable to deliver message to the following recipients, due to being unable to connect successfully to the destination mail server

This is the error message from yahoo.

I'm afraid I wasn't able to deliver your message to the following
addresses.
This is a permanent error; I've given up. Sorry it didn't work out.

<user@company.com>:
Connected to 75.xx.xx.xx but connection died. (#4.4.2)
I'm not going to try again; this message has been in the queue too
long.


On the firewall, i've let any port 25 traffic go to the Exchange 2003 server.

Anyone have any ideas on what other troubleshooting i can do on my side? Thanks.
 
4.4.2 is a connectivity issue. check dns, verify firewall rules, etc.

 
I assume you have SMTP filtering software (XWall?) and it blocks the sender domain or server IP address.
 
No SMTP filtering software.
I've checked that port 25 on the firewall is open and redirects it to the exchange server.

On my Forward Lookup Zones, i have an MX Record for mail.mycompany.com and a HOST record for the internal ip address of the exchange server.
 
In external DNS, you need an MX record, A record for the firewall external interface, and PTR record.
 
Looking at the GoDaddy account,

I have the A (HOST) setting
HOST Points to
@ public ip address

CNAMES (Aliases) setting
HOST Points to
mail mail.mycompany.com

MX (Mail Exchange)
Priority Host Goes to
10 @ mail.mycompany.com


Are those settings correct?
 
Try visiting dnsstuff.com and test your domain settings.
Still, as it was mentioned earlier 4.4.2 simply means there is a connection issue and you have to locate it.

It's not DNS since the connection is made, what matters is that it is dropped right afterwards, hence the IP block or domain filter. There really aren't many other options here. Check your PIX, ASA, or spam settings and locate the issue there.
 
I went to dnsstuff.com and ran the DNS test. I passed all the MX tests, but got a FAIL on the MAIL category. This is what it shows.

FAIL: Connect to mail servers ERROR: I could not complete a connection to any of your mailservers!

mail.mycompany.com: The mailserver terminated the connection before the transaction was complete (state 1). This is not RFC compliant, and therefore either due to an error, or it may be the result of a non-RFC-compliant mailserver or non-RFC-compliant anti-spam program.

If this is a timeout problem, note that the DNS report only waits about 40 seconds for responses, so your mail *may* work fine in this case but you will need to use testing tools specifically designed for such situations to be certain.
 
I'm still getting the (#4.4.2) error for emails from the outside. I'm just about on my wits end regarding this problem. Thanks everyone for all your input.

 
I didn't sew a PTR record. A lot of anti- spam servers will disconnect you if the reverse lookup fails.


 
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