On: How Gmail’s Image Caching Affects Open Tracking

[parhamn]

Are you sure about this? Just tested it out:

    openssl s_client -connect  smtp.gmail.com:465 -crlf

    220 mx.google.com ESMTP u17sm2709629qeb.4 - gsmtp
    helo
    250 mx.google.com at your service
    auth login
    334 VXNlcm5hbWU6
    < BASE_64 USERNAME> 
    334 UGFzc3dvcmQ6
    < BASE_64 PASSWORD> 
    235 2.7.0 Accepted
    MAIL FROM: <my_email>
    250 2.1.0 OK u17sm2709629qeb.4 - gsmtp
    rcpt to: <my_email>
    250 2.1.5 OK u17sm2709629qeb.4 - gsmtp
    rcpt to: <emaildne39g39jd9j9jfsdk@gmail.com>
    250 2.1.5 OK u17sm2709629qeb.4 - gsmtp

I get an OK with BS emails too...

[tedunangst → parhamn]

You should try telnet to port 25 and don't login. If you're sending what could be an outgoing email, it is more likely to queue it.

    MAIL FROM:<tedu@tedunangst.com>
    250 2.1.0 OK g15si484689qej.92 - gsmtp
    RCPT TO:<tedunangst1233141@gmail.com>
    550-5.1.1 The email account that you tried to reach does not exist. Please try
    550-5.1.1 double-checking the recipient's email address for typos or
    550-5.1.1 unnecessary spaces. Learn more at
    550 5.1.1 http://support.google.com/mail/bin/answer.py?answer=6596 g15si484689qej.92 - gsmtp

[parhamn → tedunangst]

Cool, thanks!