I'm experiencing very poor performances with my Mail Server when executing some specific and mandatory IMAP commands. Right now when I try to run the SELECT command on a folder with 4k+ email, the response time from the server is 2.5s . I've noticed that actually my server does not support MODSEQ/CONDSTORE so I thought that maybe this could be the issue. Is this a legit assumption? I read on the IMAP extension RFC that actually this "capabilities" allow the server and client to exchange "delta" of information instead of forcing the client to fetch again everything when trying to obtain access to a specific folder with the SELECT command.
Enabling MODSEQ/CONDSTORE on my mail server would require a lot of work, so I would like to know if I'm moving in the right direction or not.