According to the inclusion policy, all apps in F-Droid must be licensed under an FSF-approved free software license.
The FlowCrypt license is demonstrably not a free software license, as it does not grant freedom 0, the freedom to use the program for any purpose. The license places several restrictions on usage:
Use Limitation: This software is free to use with the following limitations:
- Size of any sent email message including attachments cannot exceed 5MB.
- Password encrypted messages and attachments have to expire in 3 days.
- Messages, attachments or files can only be transferred through used email provider or through services provided by Licensor. Never through 3rd party or custom services.
- Plain-text portion of password encrypted messages must only include a link to a page on flowcrypt.com domain. Recipient cannot be directed to any other place or means of decrypting password encrypted messages.
- Password encrypted messages cannot link or lead to a web page where encrypted reply is possible.
- Cannot request attestation of secondary send-from email addresses (email aliases).
- Limit one re-attestation (change of associated pubkey) per email address.
- Cannot set up a custom email footer to be included in sent messages (encrypted or not).
- Maximum 100 email addresses per domain (except gmail.com, outlook.com and other public email service provider domains excluded).