It happened overnight. I manage two e-mail accounts on Thunderbird. My secondary one is still working okay. However, my primary e-mail has started to get this message since today morning when I tried to send e-mails. The mail server responded: 5.7.1 Message contains spam or virus or sender is blocked : chair64_6c05aac9dfd4f. Please check the message and try again. I used Chrome instead of Thunderbird to send e-mail using my primary account and it sent out fine. Something in Thunderbird is block my e-mail through this account. I attempted to send an empty e-mail and it did not go through as well. So I think my email is blocked for some reason. How can I get more information on this? Thank you for your help