Used mailmate when Mail.app was slightly buggy some years ago but then got tired of mailmate being buggy as well (iirc, takes seconds selecting multiple mails,

Used mailmate when Mail.app was slightly buggy some years ago but then got tired of mailmate being buggy as well (iirc, takes seconds selecting multiple mails, changes column width after showing mail folders on/off, message signature inserting unnecessary new line and crashes randomly and never had those fixed in a year or something), I switched back to Mail.app in Sierra, seems responsive and trouble free so far.