On 2019-02-22, David Pottage via dovecot <dovecot@dovecot.org> wrote: > On 2019-02-21 22:14, Christoph Haas via dovecot wrote: > >>>> NO! My mail storage is mdbox. And at the moment I have no intention >>>> to >>>> convert it to Maildir! >>> Could I ask why? maildir is a better storage format is almost every >>> respect. >> >> well, I have a mailbox with about 50k emails ..., so one reason seems >> to me better backup performance with mdbox, since there are much less >> files to save. > > Assuming that you backup regularly then maildir is much better, because > new emails show up as new files, while old ones are left unchanged. This > means that an incremental backup only has to process new emails. With > mailbox, the file for the entire folder changes every time a new email > is delivered or the user edits any of them, so the whole mailbox needs > to be backed up again, resulting in far more I/O and time.
It sounds like perhaps you're confusing mdbox with mbox. mdbox uses multiple files but not a single file per message. It is fairly sane for backup handling - depending on how you set things up, you can have it rotate after a fixed size, fixed time, or combination. https://wiki2.dovecot.org/MailboxFormat/dbox
