Let me get this. You have trouble adding your account from some unnamed provider to Thunderbird so you are posting here to say goodbye. As you will. Goodbye I would be seeking support for why it is failing before you move on to another application that will probably have exactly the same issue as it is unlikely to be a Thunderbird issue in the end. Thunderbird is actively maintained and as far as I am aware can access ALL standards compliant mail server s(and some that are not), but that would require details of what mail provider and what error messages you get along with your use of antivirus products and VPN's BTW most account setup problems are directly caused by antivirus products that folk purchase and install Another raft are caused by VPNs and the disabling of cookies in Thunderbird for "security" reasons. You notice I do not mention Thunderbird being the problem? That is because I have not seen an instance where Thunderbird could not connect to an IMAP, POP or SMTP server with the correct settings if it is allowed to. Not for many years anyway. It has happened, but not that I can remember a specific instance. Most recently I generally I find folk trying to make two factor authentication work when they need to use oAUth authentication instead or ATT customers that do not understand the mail system their provider offers and is apparently unable to adequately describe via either their documentation or support staff.