It stores mail in the MH Message Handling System.

Sylpheed runs on Unix-like systems such as Linux or BSD, and it is also usable on Windows.

[5] Sylpheed provides support for spam filtering using either bogofilter or bsfilter, at the user's choice.

The password is stored in plaintext in the Sylpheed configuration file, which by default is only readable by "owner" and not by "group" nor "other".

[8] A feature called "master password" prevents Sylpheed from holding plaintext passwords, but does not protect stored messages from other local users with administrator privilege.