Cannot send emails using Mozilla Thunderbird
Posted by Jericho Mapanao on 08 November 2012 05:11 PM


Cannot send emails using Mozilla Thunderbird

The most common reasons for not being able to send emails through your Mozilla Thunderbird are wrong Mozilla Thunderbird configuration settings or blocked port 25 by the Internet Service provider.

Here are a few checks you can make to ensure the problem is not on your end:

Use the correct Mail Client settings:

  • Incoming mail server (POP3/IMAP server):
  • Outgoing mail server (SMTP server):
  • Username: the full e-mail address like
  • SMTP authentication must be enabled for the login to be successful.

You can find detailed instructions on how to configure your Outlook in this link: Mozilla Thunderbird Configuration

Check your port connection.

The standard port used for SMTP connection is port 25. Most often the reason for failed email sending is that your Internet service provider blocks this port. If this is the case we recommend that you use the alternative port 587 for your email SMTP connection.


Check your Anti-Virus or your Firewall.

Sometimes an Anti-Virus of Firewall can prevent your emails from being sent. This happens when your anti-virus is configured to scan all mail services being used by your computer and when a firewall is configured to block all outgoing email trafic.

To check if the Anti-virus and the Firewall are the causing the your email sending problem, we advise to stop all mail scanning services of your Anti-virus and check the configuration of your firewall settings which prevents outgoing of emails.
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