[https://support.mozilla.org/en-US/questions/1051349 (perhaps)],
[https://support.mozilla.org/en-US/questions/1041323],
[https://support.mozilla.org/en-US/questions/1055844],
[https://support.mozilla.org/en-US/questions/1050658],
[https://support.mozilla.org/en-US/questions/1050988],
[https://support.mozilla.org/en-US/questions/1051488],
[https://support.mozilla.org/en-US/questions/1054542],
{{bug|592303}}. We recommend you do all of the following:
* Disable/delete '''McAfee Anti-Spam Thunderbird Extension''' in Tools | Add-ons | Extensions (It is safe to remove the add-on, and is absolutely not needed to have excellent virus protection.)