I used to make use of a freeware called MozBackup to backup my user profile in Firefox and Thunderbird. The backup file can then be copied and restored in another computer, which is an easy and perfect migration, especially to all my emails stored in my Thunderbird profile.
Unfortunately, MozBackup has no longer been maintained since 2012. It stopped at version 1.5.2 Beta 1.
Luckily, I've found another freeware called Hekasoft Backup & Restore, which you can download here.
Hekasoft can do everything that MozBackup did for backup, restore and migration of user profiles and emails. In fact, Hekasoft supports much more software and equipped with more powerful functions.
It supports a vast variety of Chrome based (Chromium) browsers, Firefox based (Gecko) browsers, Microsoft Internet Explorer, Microsoft Edge, Opera, Lunascape, and more.
In terms of email clients, it supports Thunderbird, Postbox, eM Client, Incredimail, etc.
It also supports FileZilla, qBitTorrent, uTorrent, Skype, and some other software.
Beside the normal backup and restore of the user profiles of the same software (such as from Thunderbird to Thunderbird), either in the same computer or restoration in another computer, Hekasoft can also perform migration, optimization, plugin management, bookmark URL maintenance, and profile switching.
The "optimize" function in Hekasoft is used to clean up the caches, crash reports, telemetry, dump files, etc. of the selected software, such as Thunderbird.
The "dead link checker" will dive into the bookmark URLs of Internet Explorer, report on problematic URL links, and enable deletion to those dead links.
The "plugin scanner" is dealing with the plugins, add-ons and extensions of web browsers.
The profile switcher enable easy switching between different default user profile of the software, such as Thunderbird. You can also create new profile, clone profile, and delete profile with it.
recommend Hekasoft to be your powerful tool to perform backup, restore,
migration and maintenance to your web browser, email client, file
downloader, Skype, etc.