February 2023 - dovecot

problem converting mailbox to maildir with doveadm
by Kenneth Irving 05 Feb '23

05 Feb '23

Hello. I have an email server for testing purposes, using postfix 3.5.17 and dovecot 2.3.13. Initially, I configured postfix to use mailboxes, but now I've changed it to maildir. Emails arrive fine, and dovecot manages them well by pop3 or imap. No problems there. But I still have a lot of emails in different mailboxes which I'd like to convert to maildir. I found mb2md, which seems to do a pretty good job. Once the mailbox is converted, dovecot manages the emails without a problem. But I also wanted to learn how to use doveadm to convert mailboxes to maildir format. I read all the documentation I could find and tried to learn how this command works. I tried different combinations, but couldn't convert mailboxes to maildir. I always get error messages. I've been unable to understand why. I tried to sync, backup, and import, to no avail. I also tried dsync, which seems to have a different syntax, with the same result. Sorry for bothering you, but if you could explain to me how this command works, I'd be very grateful. Example: I have a user, let's say joe, who has a mailbox in /var/mail/joe and I'd like to transfer those emails to /home/joe/Maildir How do I use doveadm in this situation? Best regards Kenneth

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IMAP tuning for Outlook 365
by Artur Pydo 02 Feb '23

02 Feb '23

Hello, I'm looking for advices on IMAP config tuning for best user experience with Outlook 365. I'm currently using dovecot 2.3.4.1 (f79e8e7e4) provided with Debian 10. One of my users has Outlook 365 and an IMAP mailbox of large size with several folders (more than 3GB). From time to time as his main inbox folder is growing he can see some problems with its Outlook application. Sometimes it freezes during mailbox synchronisation, sometimes he can't see new incoming emails. I wonder if there is some specific workarounds for an up-to-date Outlook in Dovecot or if you can suggests some config setup adjustments (timeouts, idleing ...) to avoid problems in his Outlook. Most of the config are defaults. But I can provide relevant parts of the config if needed. I have this workaround activated for a long time: imap_client_workarounds = delay-newmail By the way, I also have a big IMAP mailbox. Can't see any server specific problem while connecting with Thunderbird to this Dovecot server. -- Best regards, Artur

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Dovecot gzip u.files on sdboxes
by Jose Celestino 01 Feb '23

01 Feb '23

Hi, I was wondering if it's possible to lighten the process of converting sdbox mailboxes to zlib by, instead of using dsync (that brings much more io, copying from alt - and copying of unneeded data as we have many mails already compressed from activating zlib a couble of years ago) just compressing each of the u files. By compression of the u files I mean opening the uncompressed u file for reading, a u.temp file for writting and: 1. copy the dbox message header from u to u.tmp 2. compress the plain message and write it to u.tmp 3. fix the message_size_hex on the u.tmp dbox message header to the new, compressed size 4. copy the dbox metadata from u to u.tmp with Zphysical_size added 5. copy the u stat times to u.tmp 6. replace u with u.tmp Is the message_size_hex stored anywhere else (indexes) that may cause this to not work? Thank you.

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