I switched to windows 10 and set up the email account originally for Gmail using POP....but I can't send emails I can receive emails but not send plus address book is empty....When I try to send a email I get the error message ".....not a valid e-mail address because it is not of the form user@host". The addresses I had in old account aren't there/didn't migrate over. Next I went to Gmail.com and see that it is set up for IMAP....so I decided to try to switch email from POP to IMAP but when I follow the Mozilla support directions I disable POP (uncheck the two boxes and save) then go to FILE but there is NO option of new existing account. I wanted to use POP so it would save the emails but Mozilla advises and now so does Gmail advise to use IMAP. Any advise on how to switch to IMAP in Thunderbird....the Mozilla support steps to switch it over didn't work as stated above Anyone know if I can change to IMAP if I go into Thuderbird SERVER SETTINGS and delete POP and I put in IMAP name and port # in box for SERVER NAME? IF that will work can anyone give me the address for IMAP and port #'s for gmail? Thanks! Ann