Per user/admin filtering of individual/group emails
FreeMe is a lightweight e-mail filtering and reorganization tool for reducing clutter and highlighting messages of interest. It is intended to allow multiple administrators to specify individual rules for handling root e-mails, but can also be used in single-user mode.
POPFile is an email classification tool with a Naive Bayes classifier, POP3, SMTP, NNTP proxies and IMAP filter and a web interface. It runs on most platforms and with most email clients.
Tarbaby is a new threshold and rate limiting spam prevention tool. The intent is in creating a thresholding and verification engine to be tied into other spam prevention tools.
SpamFox - An anti-spam tool programmed in perl Serves as a kind of proxy between your emailclient and the mailserver. Will scan messages for spam and leaves a notice if spam has been found.
Auth0 Token Vault handles secure token storage, exchange, and refresh for external providers so you don't have to build it yourself.
Rolling your own OAuth token storage can be a security liability. Token Vault securely stores access and refresh tokens from federated providers and handles exchange and renewal automatically. Connected accounts, refresh exchange, and privileged worker flows included.
Deep Six is a client side spam filtering tool that monitors your inbox for new email and filters it. The modular filter plugin-system allows for greater spam detection. Currently supports SpamBouncer, Vipul's Razor and DCC.
A mail filtering tool that uses PerlMX to allow fine-grained spam filtering controls. Utilizes host-based blocks as well as heuristics. Can be modified to use Sendmail::Milter.