IMAP login failed, mailbox missing, or mail delivered and not visible.
Dovecot is the mailbox, not the sender. Exim or Postfix can accept a message that Dovecot never shows. We separate the two before changing passwords at random.
Cannot log in, or the mail is there and the client is empty
Wrong mail location, a user the panel created and Dovecot does not see, or TLS on 993 with a certificate the client rejects. The log line names which.
After a migration the files are in the old layout. Mail was delivered. The client looks at the new path. We point Dovecot at the copy, we do not tell the user to resend a year of mail.
A full volume or a quota at the limit. Delivery fails or IMAP append fails. Freeing the disk comes before a Dovecot restart.
imapsync after the new Dovecot actually logs in
A mailbox move is a copy, then a DNS cut. We test one account on the new IP before the MX changes. Outlook profile repair is not part of the job. The server side is.
€55 an hour for a login fault. A mailbox migration is quoted.
Minimum 1 hour. The quote follows the mailbox count and the size of the Maildir, not a flat fee. Do not send the mailbox password in the first message. A test account you can delete is enough.
Clients cannot log in, or old mail vanished after a move?
Tell us the panel and whether sending still works. That splits Dovecot from Exim or Postfix.