Man pages matching name sympa::message::plugin::fixencoding in section 3sympa:

Sympa::Message::Plugin::FixEncoding.3sympa.en	debian 10 / sympa
Sympa::Message::Plugin::FixEncoding.3sympa.en	debian 11 / sympa
Sympa::Message::Plugin::FixEncoding.3sympa.en	debian 12 / sympa