I can send email when I am in North America but not when I am in Europe.
This is so odd. I am running Windows 10 on a new HP laptop. My antivirus is Avast and I am running Windows Defender. I have no problems sending and receiving email from my home network or any public networks in North America but when I am in Europe (Czech Republic, Italy, France, UK are locations where I have trouble) I cannot send email. Thunderbird displays the message An error occurred while sending mail: The mail server sent an incorrect greeting: mtlp000086 cmsmtp ESMTP server not available. I've tried turning off my antivirus and Defender. The port I am using for the outgoing mail is 587. Any help would be appreciated.
Alla svar (2)
Does your mail provider allow you to send mail when not in the US. Some providers (ISPs) will not allow you to send mail while not connected using their network.
What is the connection security and authentication type for your outgoing server on port 587? Usually, the security is STARTTLS and the authentication is normal password, but if not, that might explain why you can't send abroad.
You could add an account with a provider like gmail and send from other accounts through the gmail smtp server, and add the other account to gmail as an allowed sending address.