More information needed. If not HTML messages, there is no setting for outgoing font size. If you are referring to font size as viewed in your sent folder (which also applies to non-HTML in inbox), that is set at tools>preferences>fonts&colors. Give more info, and I'll share more along this line.

Messages go out as HTML. Look fine in my Thunderbird and sent file. Friends complain about small type size when received by them. I've changed all I know to change but am apparently missing something.

Okay, send me a message to davidtbirdhelp at gmail dot com and I'll give you specifics.

Message bounced

Address not found

Your message wasn't delivered to davidbirdhelp@gmail.com because the address couldn't be found, or is unable to receive mail.

Also, please post a screenshot of tools>preferences>composition> HTML Style

you spelled it incorrectly.

See attached screenshot. Your HTML is just as you intended, large and clear. Your HTML is exactly as I expected from your specs: Fixed width and extra large. Are your friends responding to original messages you send, or to responses to their messages to you? That can make a difference, as your response isn't guaranteed to be what you define.

Complaints are from two friends about messages I send. They don't seem to have problems with things from other people. Maybe the problem is on their end.

My suggestion: - do BCC on emails to your friends so that you see exactly what they see. Browsing your sent folder should be sufficient, but viewing in inbox will be more reassuring.

Thanks. Will do.