Gmail uses different ports for its POP3 and SMTP connections. Gmail requires users to connect to POP3 via port 995 and SMTP via port 587.

However, many companies firewall block traffic from accessing through non-standard ports. The standard ports for POP3 is port 110 and SMTP is port 25.

WebMail is an Mozilla Thunderbird extension that allows users to integrate web-based e-mail accounts such as Gmail, Yahoo, Hotmail, and many others into Thunderbird. It uses standard HTTP protocol to
connect and access your web mail account. Most companies enable HTTP traffic to pass through the firewall.

WebMail is the solution for you to connect to Gmail account to send and receive e-mails if your company firewall blocks those non-standard ports.

Follow these steps to setup WebMail extension in Mozilla Thunderbird.

Step 1
Download and install the latest Webmail add-on extension for Thunderbird at http://webmail.mozdev.org.

Restart Thunderbird after the installation is completed. The WebMail extension must be installed first before proceeding to step 2.

Step 2
Download and install the Gmail, Hotmail, Yahoo, and etc. extension components at http://webmail.mozdev.org.

Restart Thunderbird after the installation is completed.

Step 3
Setup new account in Thunderbird. Enter localhost for both POP3 and SMTP server setting. For information about the settings, please refer to this link.

Step 4
Check the box to leave a copy of the e-mails in the mail server. This is optional if you wish to have a copy of the e-mails save in your Gmail account.

Step 5
Save your settings.

Happy e-mailing!