Do you send through a Yahoo-type account?

https://support.mozilla.org/en-US/questions/1247134#answer-1189872

ATT is the email server. Could be connected through YAHOO as it is also a default email option. I read the offering yet I am running THUNDERBIRD email and the options being offered are either not available or not offered. Thanks for your reply and offering support. Any additional info would be helpful.

BACKGROUND

I was using OUTLOOK 19 as my email platform. After an upgrade, the SEND option appeared to get corrupted and I could not longer send emails. I transitioned to Windows MAIL but the platform was not user friendly; messages were delayed and could not send attachments without experiencing conflict Contacted ATT on another matter and inquired if they offered a email platform. They offered THUNDERBIRD. Downloaded the program and have been using it until some friends advised me of the 'weird characters' that were being included in my emails.

Hope this helps.

THANKS IN ADVANCE!

Did you follow the instructions provided above? The Config. editor is under Options/General, at the bottom, in TB 78, and Options/Advanced/General in TB 68. AT&T email is a Yahoo system.

YES!! OUTSTANDING!

I was able to find the CONFIG EDITOR but had some additional steps getting there:

I opened WRITE (dialog box to send a message). On the tool bar, then I selected TOOLS - OPTIONS. On the LEFT SIDE of the next dialog screen located GENERAL. Once there, I scrolled to the bottom, and near the right of center, I located the CONFIG EDITOR. Once confirming there was a risk in entering this area, I followed alphabetically where I was able to locate the MAIL.STRICTLY_MIME line option. Once located, I double clicked on the line which changed the function from FALSE to TRUE. I then backout of the screens and restarted THUNDERBIRD. Will monitor the activity from here on. MANY THANKS FOR THIS EXTREMELY VALUABLE SUPPORT!