Anyone using "Pandora" email client with "TalkTalk" ISP (UK) and can help us get sending working?

My blind friends have been using the "Eudora" email client for many
years, and it still works; however, it is beginning to have problems,
for example with security certificates. (It ceased development in 2006,
so it's not doing bad!)

Changing software is difficult for many of us, but more so for the blind
- they have learnt how to navigate round the software using keyboard
only. I was aware that Eudora was having problems, so was pleased to
read about Pandora, which was claimed to be very usable by those used to
Eudora, and still being supported/developed (it claims to work on at
least XP to 10, and I think some other OSs [Julia uses 7-64]); however,
I just told my friends about it, to let them if they wanted have a look
and decide. (We've been burned by a claimed replacement before.)

Julia has downloaded, installed, and configured it (she's quite computer
literate), and quite likes it; however, she can't get it to _send_
emails - and neither could I, in a Teamviewer session. (_Receiving_ is
working fine.)

I think the problem is that Pandora is more versatile, to cater for the
authentication requirements ISPs use these days. But we _think_ we've
tried all the permutations!

http://255soft.uk/temp/Clipboard01.jpg shows the configuration window,
as well as one of the error messages we get, in the log window at the
bottom.

There _seem_ to be three areas to play with, giving in theory 18
permutations:

"Authentication", which can be Basic, MD5-something, or OAuth2;

"Secure Sockets when Sending", which can be Never, If Available
(STARTTLS), or Always;

and "Include on global send", which is a tickbox.

Unticking the last seemed to prevent Pandora even trying to send when
told to (nothing appeared in the log window). I'm pretty sure I tried
all 9 combinations with it ticked.

Selecting OAuth2 generated an error message something like "unrecognised
authentication method".
TalkTalk's setting page at
https://community.talktalk.co.uk/t5/...3/ta-p/2204399
says don't use MD5, but I tried it anyway - I forget what error message
we got, but it didn't work.

Looking at what Julia had set in Eudora, "If Available" was set. As you
can see, that - with "Basic" - generated "5.7.0.7garbage
Authentication Credentials Invalid (TT300) [535]".

Some of the other combinations generated "Invalid Command" (I think with
"504").

You'd think the meaning of "credentials invalid" is obvious - username
or password are wrong; but (a) the same ones work in Eudora, (b) they're
working for _sending_.

Any thoughts? (Especially if you use Pandora with TalkTalk!)

(The above settings page just says "Outgoing START/TLS: Yes, Outgoing
Authentication: Yes" - nothing about which _type_ of authentication. But
the text below the table says don't use MD5, and selecting OAuth2 gave a
message implying that wasn't recognised, so Basic seems the most
likely.)
--
J. P. Gilliver. UMRA: 1960/1985 MB++G()AL-IS-Ch++(p)Ar@T+H+Sh0!:`)DNAf

Politics: A strife of interests masquerading as a contest of principles.
- Oscar Wilde, quoted by Ron Bauerle 2015-7-24