outgoing SMTP attachment size?

[nsr500]

Outgoing to mail.sonic.net via port 587+STARTTLS with a relatively small attachment (1.5M jpeg, 1.9M after encoding) will consistently fail due to SMTP timeout, yet the same attachment sent via port 465+SSL/TLS goes through.

Any primary guidelines for using one over the other?

General attachment size guidelines?

Cheers,
Tim.

[kgc]

Tim, using the submission port, 587 is the right thing to do. However, if you are having trouble using it there is really nothing wrong with using 465. Max message size is limited to 30MB. What client is sending the mail? If you wouldn't mind trying again I'd like to see if I can find an error on our end. Just let me know the date/time of the a failed attempt.

[nsr500]

I use 587 due to frequently being on different networks, the mail client is seamonkey 2.9.1.

I'm synced to time.sonic.net and will try 587 settings three times in a row to my email account beginning at 11:35am.

Cheers,

[nsr500]

As these things go, it actually worked this time on 587. I'll bump up the attachment size a few hundred KB and retry at 11:40am

Cheers,

[nsr500]

At 11:40 I sent 3 test emails to my sonic account using 587, then a 4th using 465, with a 2MB jpeg attachment (about 2.6MB encoded).

In this case all 4 failed at between 60 and 62 seconds after hitting 'send'. The mozilla mailnews.tcptimeout value was changed from 5 to 120.

Cheers,

[nsr500]

Heavy solar flares today???

I just checked and in spite of the warning all test messages actually made it through. Might be a mozilla oddity. Unfortunately I can't test another agent at this time.

Cheers,

[kgc]

No problem, please do let us know if you run into the issue again. (mail.sonic.net has no relation to the mail cluster we upgraded yesterday.)

[nsr500]

For completeness, the exact error message is:

Sending of message failed.
The message could not be sent because the connection to SMTP server mail.sonic.net timed out. Try again or contact your network administrator.

Cheers,