When comparing Mozilla Thunderbird vs Calibre, the Slant community recommends Calibre for most people. In the question“What are the best RSS readers for UNIX-like systems?” Calibre is ranked 4th while Mozilla Thunderbird is ranked 6th. The most important reason people chose Calibre is:
Features include metadata editing and downloading, coverpage downloading., book tagging and categorization, webpage-to-ebook converter for popular websites, etc. Lots of plugins available to extend functionality.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Free (as in freedom and beer)
Pro Available on Linux, OS X and Windows
Pro Very reliable
Version after version, Mozilla Thunderbird works as expected.
Pro Good filtering system
Mozilla Thunderbird offers a flexible filtering system with the ability to set flags and read/unread, as well as sort/assign to new mail directories. There are also numerous plugins available to assist in the filtering.
Pro Large assortment of plugins available
Mozilla Thunderbird offers a huge amount of extensions to expand the usability and options of the client.
Pro Great flexibility
More options and extended settings than most power users could dream of. Get it working how YOU want.
Pro Tabs for navigation
Pro Lightning Calendar and Address Book integration
Pro Consistent and involving a moderate learning curve
The app design of Mozilla Thunderbird has not changed significantly since its beginning, making its learning curve almost non-existent.
Pro Send large files easy
Install pCloud plugin for Thunderbird and your files (upto 20 GB free storage included) will be received as download links
Pro Powerful book management software, very customizable and scriptable
Features include metadata editing and downloading, coverpage downloading., book tagging and categorization, webpage-to-ebook converter for popular websites, etc. Lots of plugins available to extend functionality.
Pro Cross-platform
Calibre is available for Linux, OS X, and Windows, 32-bit or 64-bit.
Pro Open Source
Pro Portable
Calibre has an optional portable build that can be stored on external media along with the users library. It can then be opened from the external media on any windows device.
Cons
Con Development slowed to only focus on stability and security
Mozilla Thunderbird has slowed down its development of features to only focus resources on security and stability.
Con Outdated interface
Thunderbird's interface is very outdated and unpleasant. It feels more like a Windows XP application than like a modern MacOS one.
Con Terrible integration with macOS
Simple things - drag/dropping pictures doesn't work, for instance.
Con Subject lines can (temporarily) disappear from the list
This is sporadic behavior.
Con Serious bugs
Clicking on a subject line can bring up the wrong email.
Con Average, non-power users might find the interface somewhat daunting
The interface, while functional is not the most attractive or intuitive which may put some people off and discourage their use.
Con Can't save text highlights or annotate
