What exactly happens when you try to send a message? Who is your email service provider?

I am unable to send emails on Thunderbird. Is there a fix? Thanks. I have "Outlook". When I try to send a message on thunderbird, this message pops up: "The message could not be sent because connecting to the Outgoing server (SMTP) 587 failed. The server may be unavailable or is refusing SMTP connections. Please verify that your Outgoing server )SMTP) settings are correct and try again."

Post all your replies here and NOT in a private message.

Go to Thunderbird's menu > Help > Troubleshooting Information > Mail and News Accounts. Select everything in that table and paste it in your reply.