When comparing Claws Mail vs Tutanota Mail, the Slant community recommends Claws Mail for most people. In the question“What are the best e-mail clients for Windows?” Claws Mail is ranked 6th while Tutanota Mail is ranked 14th. The most important reason people chose Claws Mail is:
Claws Mail is a low resource e-mail client that is often default in low resource Linux distributions.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Low resource client
Claws Mail is a low resource e-mail client that is often default in low resource Linux distributions.
Pro Open-Source
Pro Has many plugins for extra functionality
Pro Traditional user interface
Pro Clean interface with 5 layout variants

Pro Saves emails in uncompressed readable format
Allows one to read archived emails with a text editor.
Pro Has very strong filters
The filters a much stronger than in thunderbird.
Pro Saves passwords in encrypted format
Pro Has many themes
Pro Also supported on Windows
This makes switching the platform easier.
Pro Good support for Google's services
Pro End to end encryption
End-to-end encrypted:
- internal emails (between Tutanota users)
- external emails: requires setting a password and sharing it separately to the recipient
- calendar
- contacts
- email storage
- email subject lines
Pro Open source
See here.
Pro Based in Germany
Tutanota's servers are located in Germany, which has strict privacy protection laws, even stronger than those of Switzerland.
Pro F-Droid app
Pro Anonymous: no personal information and no phone numbers are required to register
Pro No offices in the USA
Pro Free
A free account is available.
Pro Add free
Pro Desktop client
Pro U2F for second factor authentication
Pro Affordable price for paid plans
Cons
Con Blocks and freezes all the time
Con Saves passwords in plain format
Con Too much bloat
some people dont like the simple design of slypheed so they forked it and created claws mail but it has become so bloated since itsbeginnings.

Con Saves emails in uncompressed format
This takes more space on the HDD.
Con Interface looks old and setup is not easy
The icons as well as the rest of the interface look like an application from the early 90's, with this there is also no easy setup options built in like the more modern e-mail clients.
Con No support for third-party clients (eg Thunderbird...)
Con Doesn't support PGP encryption
Con No support for IMAP and SMTP
You can't use your favorite email client.
