Hello There!

OVERALL, 3 MAIL Accounts have been configured within Mozilla Thunderbird vide my ISP one(POP), Gmail(IMAP) & gmx.com(POP). How to decide that which one of the 3 respective SMTP Servers should be made the "Default SMTP Server"??

Secondly, what exactly one means by the "Default" SMTP Server?...because each of the Mail A/c ultimately uses its very own SMTP Server to deliver a Mail.Then, how does the question of "Default" arises over here? It just wants to know which of those will be used the most, or set up as an initial or primary account.Default SMTP server may have its own meaning in terms of how thudnerbird sends mail. For example, if you're default account is google then whenever you send mail it will use google to send email and ignore the others even though you may want to send email from another account. I have often OBSERVED that if "FROM:" address is suppose that of Gmail ID & the default SMTP Server is set to someone's else, then the 'Sent Mail' often LANDS in the JUNK Mail folder of the recipient!

Do both of these  needs to be synchronous i.e. of the same service provider?