Hi, I have a strange issue, and another Thunderbird user I know has the same one. When we have an email exchange with someone, the third (I think) time we hit "reply" to the email thread, we receive the error message that the SMTP server timed out (below). We can open up a new email, starting a new thread, and send it to the same recipients, but under no circumstances can we continue to reply to the same thread using Thunderbird. On the other hand, we can reply using our phones or webmail. Also, I tried to copy and paste the thread into a new email, and it also could not be sent with TB. We are both using Windows machines, I'm using W10 and the other person W7. We have also tried multiple smtp servers, and have tried multiple internet servers. Always the same result. Again, the problem is limited to replying the (I think) third time to the same email thread. Thanks for any insight! The error message is: "Sending of the message failed. The message could not be sent because the connection to Outgoing server (SMTP) smtp.utoronto.ca timed out. Try again."