Methods to fix Mozilla thunderbird not sending emails problem Below is the screenshot containing the probable statement for this error. This error comes up due to as the ISP hunks the outgoing ports as a guard against the connections, which are utilized to spread spam. It is SMTP that manages the whole delivery system. This error is faced by Thunderbird users because of server issues in the SMTP (Simple Mail Transfer Protocol). Reason behind Mozilla thunderbird problems sending emails We will cover all the reasons behind this error and how to resolve it. If you also belong to the same category as this user then this blog will help you out. I am stuck in this problem and not able to find a solution for it? Can anyone help me out regarding this? “ I contacted my ISP regarding this error, they just checked it out and said that nothing is wrong from their end. Whenever I try to send an email via Thunderbird it displays an error “Try again”. “ I am receiving my Thunderbird emails properly but I am unable to send mails for the last two days. But still, Thunderbird faces many problems and one of them is Mozilla thunderbird problems sending emails which we will be covering in this blog. Thunderbird users have complete ownership over the email messages and offer numerous other benefits and functionalities. Thunderbird is a free open source platform developed by Mozilla Corporation that functions as an email client, news client, RSS, and chat client.