I can confirm that my SMTP settings have 'Use same settings as my incoming mail server' highlighted.
I've had problems with openssl as this doesn't appear to have an application interface. When I enter the text you have supplied into the command window, I get ''openssl' is not recognized as an internal or external command, operable program or batch file.' Do I have to execute the openssl application and enter the command there?
I'm not sure whether I need to do everything you've mentioned below. If this is just to get rid of the return code 20, which you indicate is an issue only with openssl, then is there any point me going through this? I'm afraid I'm not a techie like you so, once the problem is resolved, I will probably uninstall openssl.
I'm not sure where all this has got me. On the send, it seems there is a disparity between my credentials and what virginmedia is expecting, though I have made no change to my credentials and they appear to be correct. Presumably this will have to be thrashed out with the virginmedia tech team.
Do you think that the receive errors are related to this and will be corrected once the send issue has been fixed?
As a final attempt to resolve, do you think there is any value in me removing the account from Outlook and then adding it back in again? I would have tried this approach already but I was concerned that I may lose all of my emails. I can back them up to a .pst file, but do I also need to do anything with the .ost file?
As no-one has posted anything for a couple of days, I presume you have moved on to other issues.
HowardML warned me this was a difficult problem, but thanks for trying to resolve it for me. I know you're all interested volunteers, so appreciate your help and advice. I'll see whether the virginmedia tech team can find a solution.