Please let me know what to do, I have to work and send emails and this is coming up. Thank you! An error occurred while sending mail. The mail server responded: VnMZdVZAs0zuv :: auth :: Message rejected for spam or virus content :: Please include this entire message when contacting support :: v=2.1 cv=TudG/Gjh c=1 sm=1 tr=0 p=_ZZmFtwPAAAA:8 a=c0b9EaLUQPu8ArZzKGCQqg==:117 a=c0b9EaLUQPu8ArZzKGCQqg==:17 a=L9H7d07YOLsA:10 a=9cW_t1CCXrUA:10 a=s5jvgZ67dGcA:10 a=IkcTkHD0fZMA:10 a=h2Lq3oj-AAAA:8 a=mWNwH6VaAAAA:8 a=6wkfAn-wAAAA:8 a=CjxXgO3LAAAA:8 a=DhVZHDMyAAAA:8 a=3j4BkbkPAAAA:8 a=JqEG_dyiAAAA:8 a=HSUpDp8UAAAA:8 a=BkpHzsgbAAAA:8 a=jU4qhlNgAAAA:8 a=5IQnDi6DpfJZ0eP_A24A:9 a=vw6iwVVO5kbN4bvWlfsksWyUBTs=:19 a=mr7UayG8oM6LZRdLZkxIgYpTFvM=:19 a=uvj8yKJKK7lhIVAK:21 a=lItP2ZyvX4oUxZ8R:21 a=QEXdDO2ut3YA:10 a=mL1p19sO6ygA:10 a=rK5crTpo5CgA:10 a=UrpsKkmaxuYA:10 a=EOjvdkaVoNUA:10 a=Niv13dkH-WcA:10 a=5IGdCKagUE8t2vaJlqYn:22 a=j51JacMR9MiFrptViZMZ:22 a=H_I5DpbS0gQ4fOf9vcs2:22 a=AMuijMv9fZVUgF0nu6dU:22 a=02ZnhTUNWO0bufAgHRyl:22 a=l_HwgdHS4zOrn5xvPxF0:22 a=44MtXGwT5FfNqG22yvD2:22 :: 100.00. Please check the message and try again.

What anti virus are you using? There was an instance of mail rejected by the supposed SMTP server caused by Kaspersky earlier in the week. Although the mail was never leaving the machine or getting submitted to the server.

Otherwise the error is from your mail server, Thunderbird is but the messenger of what the serer said, so you should contact their support with the details.

Having said that any information you can offer as to the cause is welcome.