If you are receiving email that says it is FROM your email address and TO your email address and you have definately not been sending them as test emails, then it is highly likely that some nefarious person is abusing your email address. Usually, they get bored after a while and stop, but you must not respond to them nor open them nor click on any content therein as this may make you vulnerable to malware or allow the abusive sender to know their intended victim - that's you - fell for their tactics and that your email address is a real email address which they can then send to other people. If your server gets loads of these spam emails apparently being sent from your email address, you could get blacklisted for sending spam. You should never open any email that sound dodgy and if you do, then never click on anything within the content of that email because it can open links you do not want. Remember, you can hover over a link and the true link will display in the bottom Status Bar. Your comment sounds like you have been opening these emails and perhaps clicking on bad links. It is important that you do not allow remote content to be auto displayed. Thunderbird does not allow remote content to be displayed by default, but you can over rule this - I suggest you do not unless you really know the sender is a safe sender. At this point: * Delete any emails you think are dodgy. * Empty the 'Junk/spam' folder. * Empty the Trash folder. * Compact all folders to remove any hidden marked as deleted traces of all deleted emails. Exit Thunderbird. Restart your computer in 'Safe Mode'. Run your Anti-virus and any other Malware removal software you have on computer. Once this is done and all is ok: Restart computer in normal mode. Logon to your webmail account via a browser. Change the password. Then start up Thunderbird and update the stored password.