Mozilla Thunderbird is a free email client designed by the not for profit Mozilla Foundation. It is the most popular free to download email client outside of those provided by Microsoft and Apple and is widely used throughout the world.
Before following the below step by step guide, please find the email sent to you which contains your email settings.
Step by Step Guide
In Thunderbird, click the burger menu in the top right.
Select Options and click Account Settings.
Select the Account Actions drop down menu and click Add Mail Account.
Fill in your account details.
Your Name: your name as you wish it to appear on outgoing email messages
Email Address: your email address
Password: your email address password (found in the email we sent you with the subject line 'Webmail / IMAP - [Your company name]')
When you have entered the relevant details, click Continue.
Check you have the following account settings:
Incoming mail: IMAP
Server host name: zimbra.protectedservice.net
Port: 993
SSL: SSL/TLS
Authentication: Normal Password
Outgoing mail: SMTP
Server host name: smtp.protectedservice.net
Port: 587
SSL: STARTTLS
Authentication: Normal Password
Username: Incoming and outgoing are your email address
When you are sure these are correct, click Done.