Google Mail SMTP Reports Success, Fails to Deliver

Surely at on point you've used an automated system to send messages via Google Mail (GMail). Eg, using ssmtp with Google Mail. We do it too, but have noticed that many times Google Mail will report a successful receipt but never actually delivers the message.

I wonder how many communications have been lost due to this?

Note: this happens when using their Gmail or Google Apps systems - Standard or "Enterprise".

Symptom Mail Logs

Here is a snip from a verbose mail log, which shows Google reporting successful receipt of a message. Names have been changed to protect the innocent.

~ # echo -en "Subject: Test Demo 2326\n\nTest Demo Machine" | sendmail rcpt@edoceo.com
sSMTP[15508]: Set HostName="demo.edoceo.com"
sSMTP[15508]: Set Root="host@edoceo.com"
sSMTP[15508]: Set MailHub="smtp.gmail.com"
sSMTP[15508]: Set RemotePort="587"
sSMTP[15508]: Set FromLineOverride="True"
sSMTP[15508]: Set AuthUser="sender@edoceo.com"
sSMTP[15508]: Set AuthPass="complicated-password-here"
sSMTP[15508]: Set UseSTARTTLS="True"
sSMTP[15508]: Creating SSL connection to host
sSMTP[15508]: 220 mx.google.com ESMTP hh2sm2028847obb.1
sSMTP[15508]: EHLO demo.edoceo.com
sSMTP[15508]: 250 ENHANCEDSTATUSCODES
sSMTP[15508]: STARTTLS
sSMTP[15508]: 220 2.0.0 Ready to start TLS
sSMTP[15508]: SSL connection using RSA_ARCFOUR_SHA1
sSMTP[15508]: EHLO demo.edoceo.com
sSMTP[15508]: 250 ENHANCEDSTATUSCODES
sSMTP[15508]: AUTH LOGIN
sSMTP[15508]: 334 XXXXXXXXXXXXXX
sSMTP[15508]: XXXXXXXXXXXXXXdmlzdGNlbnRyYWwubmV0
sSMTP[15508]: 334 XXXXXXXXXXX
sSMTP[15508]: XXXXXXXXXXXXXXNpZ2FyLXBpenph
sSMTP[15508]: 235 2.7.0 Accepted
sSMTP[15508]: MAIL FROM:<sender@edoceo.com>
sSMTP[15508]: 250 2.1.0 OK hh2sm2028847obb.1
sSMTP[15508]: RCPT TO:<rcpt@edoceo.com>
sSMTP[15508]: 250 2.1.5 OK hh2sm2028847obb.1
sSMTP[15508]: DATA
sSMTP[15508]: 354  Go ahead hh2sm2028847obb.1
sSMTP[15508]: Received: by demo.edoceo.com (sSMTP sendmail emulation); Wed, 11 Apr 2012 06:37:14 +0000
sSMTP[15508]: From: "root" <root@demo.edoceo.com>
sSMTP[15508]: Date: Wed, 11 Apr 2012 06:37:14 +0000
sSMTP[15508]: Subject: Test Demo 2326
sSMTP[15508]:
sSMTP[15508]: Test Demo Machine
sSMTP[15508]: .
sSMTP[15508]: 250 2.0.0 OK 1334126238 hh2sm2028847obb.1
sSMTP[15508]: QUIT
sSMTP[15508]: 221 2.0.0 closing connection hh2sm2028847obb.1
sSMTP[15508]: Sent mail for root@demo.edoceo.com (221 2.0.0 closing connection hh2sm2028847obb.1) uid=0 username=root outbytes=428

Notice the line right before QUIT, where google reports 250 2.0.0 OK 1334126238 hh2sm2028847obb.1.

Wait as long as you like, the message never arrives. It doesn't go to SPAM, it doesn't get accidentally labeled as something else. It just disappears.

I've run this same test agains multiple target accounts in Google Mail systems, across multiple domains. I've run this test from various domains, from various servers and server-configurations.

However, I cannot predict when/how this will happen. So far it's happend with mulitiple SMTP softwares including ssmtp (as above), postfix, PEAR::Net_SMTP, radix_mail_smtp and also seen this occur from the Gmail application on an Android device. Haven't had a report of this from iPhone (yet) - but we just started tracking.

Also note, the issue is not consistent. For example the test message from above failed, but after I went to have a pint across the street and came back message would be delivered. Previous messages were still lost.