I posted a similar question earlier, and although I never got any useful advice, the problem of random emails disappearing from my PC seems to have resolved itself after a week or so. However the problem has now turned up again, but this time on my husband's PC (both PCs are running Windows 10 and latest version of Thunderbird). None of the three accounts on his PC is receiving emails, although Thunderbird correctly enters the number of 'unread' emails and updates it when more arrive. The emails '''do''' arrive on my own PC and on my Apple devices (all of these also receive email for all three Thunderbird accounts), but they do not arrive on his desktop PC: the only way he can read his email at present is for me to forward it from the inbox on one of my devices to his Gmail account. If I do this, Tbird seems to recognize that the email has been opened and read, and on his PC the number of unread messages is updated (it might be worth noting that the number appears in grey, not blue as usual). He is able to send new emails from Tbird, although of course he is unable to reply to the messages that are not displayed there. It is particularly annoying because most of the missing mail is either business related or updates on medical appointments, etc. I really cannot understand this problem, and am probably not explaining it very well. Thunderbird on his PC seems to recognize that new emails are coming in to all three accounts, because the number of unread messages updates, but the messages themselves are not being displayed (I've looked for them in junk, deleted, etc., but no luck). There are no filters set up to redirect things (except a few to send scams to junk). And all the emails are coming in fine to all three accounts on my PC, as well as my Apple devices & our server's webmail function. If anyone can help, we would be very grateful. We are long-time Thunderbird users, and would hate to have to give it up and learn something new. Many thanks.