Problem after migrating imap account to new server

Hi,
I am posting this here because I am at this point unsure if the problem is the Migration Tool, Dovecot or Outlook.
We have a client who has two Email-Accounts with us, one for himself and one for his secretary. Today I migrated the client "migrate --only-client=customer_xxx" to our new mailserver. No error messages Now we have a problem I dont entirely understand. After exchanging the connection settings on the client's pc all of his incoming emails were downloaded again including - at least that was my impression - his sent email folder. I was therefore under the impression that if everything was downloaded again that it made more sense to delete the account on his secretaries pc first and then recreate it, thereby avoiding the problem of the duplicated incoming folder. This is exactly what I did and now she has her incoming folder but not her sent file. I was under the impression that when using IMAP one usually gets a copy of sent email on the server. I connected to the old server with Thunderbird and also only received the incoming emails.
Am I correct in assuming that Outlook even when using an IMAP account stores outgoing email only locally and not on the server and that therefore one can't really migrate one client's email in its entirety? (Which means of course Outlook is at fault, not Dovecot and not the Migration Tool).

Yours sincerely
Stefan

 

No, I moved from Dovecot to Dovecot and ispconfig3 to ispconfig3 and Outlook started downloading the messages right after I changed the server settings from the old to the new server. This happened both with the client's pc and the pc of his secretary. Do you know any tool which which I can browse the maildirs on the server? I would like to check the the users accounts and confirm that Outlook did not save outgoing messages on the server.
Yours
Stefan

 

My undestanding is doveadm is the suitable tool.
https://wiki2.dovecot.org/Tools/Doveadm
Also ls shows what files are in the subdirectories of the mailbox.

 

Solved: The accounts on the old server were configured as POP3 while I instinctively used IMAP when configuring the accounts on their pcs. Now both are back on POP3 and all problems disappear.