can't send mail to gmail only - no errors (Full Version)

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smig -> can't send mail to gmail only - no errors (28.Sep.2009 12:36:20 PM)

Hi.

I can't send mail to gmail, I can send mail to every other isp except them but the worst part is that there are no errors. If I check what happened to my emails on the tracking center it ends up with "Message transfered to mx.google.com through SMTP"  so apparently the messages are sent and accepted by gmail's servers but they never show up in the gmail mailboxes that they were sent to.

Any ideas about how I should troubleshoot this?




smig -> RE: can't send mail to gmail only - no errors (28.Sep.2009 12:45:03 PM)

After I wrote that I decided  to check whether mx.google.com existed and it doesn't seem to exist. It's not even listed as an mx record on neither gmail.com nor google.com. Is this significant or is it just the way their servers decide to call themselves? Can this be part of the problem?




uemurad -> RE: can't send mail to gmail only - no errors (28.Sep.2009 1:10:57 PM)

In cases like these, here's what I do:

First, verify the FQDN of the recipient domain's MX record using NSLookup.
Second, send a manual test message to that FQDN using Telnet.

That being said, you are correct in that mx.google.com is not the FQDN for Google's mail.  You are also correct to assume that it is part of the problem.  It means that you have incorrect DNS information.  Are you getting it from the public DNS systems, or do you have a local static entry either on a local DNS server or in a HOSTS file?




smig -> RE: can't send mail to gmail only - no errors (29.Sep.2009 7:10:07 AM)

I did some more troubleshooting and I'm really confused now. I started by comparing the mx records using nslookup on the mail server with the mx records returned by an online tool like mxtoolbox.com and although they're the same, the A records point to different ips. For example, the first record is:
gmail-smtp-in.l.google.com 72.14.221.114 (on local server) and 209.85.211.27 (on mxtoolbox)

I thought I had identified a problem so, although I don't know what's causing it, I started using another DNS server that had the correct information but the problem remained! Then I've tried to send an email using telnet to the correct gmail's SMTP server and using its IP address to circumvent any DNS issues and the result was the same as with the emails sent through exchange: it accepts the email successfully, returns no errors but it never shows up on the gmail mailbox neither in the original mailbox as a NDR. It tells me that it went through but then, somehow, it silently drops is after the transfer (isn't this against some RFC?)

At this point I did another thing, I tried sending the email from my desktop pc at work and it finally showed up in my gmail mailbox. I'm thinking now that the only reasonable hypothesis is that it's some kind of spam check on google's part that rejects the IP address of the server since that's the only difference between the telnet tests I did on the server and the one's I did on the desktop pc.

About that mx.google.com I talked earlier, all of their servers introduce themselves as mx.google.com from within the SMTP session so I think that's what is supposed to appear on the tracking center log and not the actual FQDN of the server so I don't think that's the problem.

Do you see any other problem? Without a NDR stating the spamlist in question I can't do anything else to know if that's the problem other than changing the outgoing gateway but I can't do that immidiatly. This is the only domain which I'm having trouble with.




uemurad -> RE: can't send mail to gmail only - no errors (29.Sep.2009 10:20:06 AM)

First, check your SMTP logs to see if your server thinks it successfully delivered the message to Google.  Assuming that it did, one of things that Gmail does is performs a reverse DNS check from the sending address.  Do you have a PTR record configured for the public IP address from which your mail appears to come?

Apologies for the wording of that last sentence, but it's not accurate enough to say the public IP address of your Exchange server because you might have a firewall/router NAT in place, or you might be sending your mail through a smarthost of some kind.  To the outside world, your mail comes from a particular static, public IP address assigned to you by your ISP.  You need a DNS PTR record for that address.




MxToolBox -> RE: can't send mail to gmail only - no errors (1.Oct.2009 4:46:24 PM)

There are a couple of things you can do to diagnose your outbound mail flow. First, you want to confirm your outbound IP address. You can do that by sending an email to ping@mxtoolbox.com. This tool will automatically reply back to you with your outbound headers and your public IP.

If your server is using the same IP for both inbound and outbound, then the easiest way to test your Reverse DNS records would be to run a SMTP Diagnostic. If you are not using the same IP for both, then you can run a Reverse DNS check manually. You want to have a Reverse Lookup that has your domain in it for best delivery performance.

Lastly, we would recommend running a Blacklist Check on your IP to see if it might be listed on any reputation based lists.

If you want to provide us with detailed information offline, then you could email us at support@mxtoolbox.com and we would be happy to try to help.

Thank you,
Wendy




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