I accepted the upgrade of Thunderbird 78 and after that I cannot send emails. I can receive, but not send. I have checked with my provider, RCN and all is well on their end. I have checked with my security NORTON, and all is well on their side, even disabled the firewalls to prove it. So, there is something stopping email on Thunderbird side. I am not a techy person, so I need some serious guidance to know what to look at or to look for. and I am very very frustrated at this time. Thank you. I am unable to upload the pdf of the snip for you review: It Reads: Sending of the message failed. The message could not be sent because connection to Outgoing server (SMTP) smtp.rcn.com failed. The Server may be unavailable or is refusing SMTP connections. Please verify that your server (SMTP) settings are correct and try again. Thank you for your assistance.