''''''Google translated:''' '''Hello, Thunderbird sent mail seems to be sent, but it is not sent to the outgoing ones. And when you receive an e-mail, it does not go to your inbox.'''''' You need to contact your POP3/IMAP email provide to get the correct settings to insure thunderbird connects to your POP3/IMAP email server. This isn't a Firefox or Thunderbird issue but a setting issue that your ISP Email provider need to help provide the settings to connect to your ISP email.