John Mc wrote:

I am retired, and this notebook computer goes with us to various
places on short-term vacations. So, unfortunately, I have no known
"work ISP" at our varying destinations. Therefore, it seems that my
practical options are your suggestions 3a (which I will pursue), 3b
(which I'm now doing, clumsily), and 3c(1). I want nothing to do with
AOL.

If you are traveling with your PC and connect to different ISPs, then you
must either change your account to use the SMTP server of the ISP to which
you connect, or you must properly authenticate to your own server. Many
ISPs do not like to transmit messages on their networks that appear to come
from another network.
--
Brian Tillman [MVP-Outlook]