My primary email is with Comcast (aka Xfinity) A short while ago, even though I was successfully receiving emails, I am unable to send emails from that account. I've verified my SMTP settings, and nothing has changed in any of my account configurations. The only way I am able to send or respond to emails is by using Comcast's webmail interface. I've been happy with Thunderbird for many, many years, but am very frustrated. I'd appreciate any assistance.