apt install sylpheed sylpheed-doc sylpheed-plugins sylph-searcher
account settings user-defined header: X-Mailer Sylpheed common preferences Receive// auto check 5 min check new on startup update after incorporation incorporate from /var/spool/mail Send// General notify when: pièce,jointe,annexe,attach Compose// Spell checking enable default en Display// General monospace 10
about certs for windows https://sylpheed.sraoss.jp/en/news.html