Post Migration Tool - login changed, dovecot error, password error

Hi,
Post using your migration tool from cpanel to ispconfig, I am facing the following issue:

1. The login to user email used to be [email protected] under cpanel. However when i look at the list in ispconfig, it shows as something else. Example the user in cpanel was "[email protected]", and in ispconfig it shows as "sales_2". Is this normal ? Would I have to go in and change each username to be as the full email ID ?
2. The password from cpanel server doesn't seem to be working on ispconfig. Maybe i misunderstood about the migration tool will help us copy the password as it is. Is it correct ? Do we have to reset each and every password for user ?
3. Dovecot is giving "Corrupted index cache file" when accessing webmail. I searched and found this thread - https://www.howtoforge.com/community/threads/dovecot-error-failed-input-output-error.72097/. The server is a new VM, so data corruption is not possible. Yet i followed the instruction and removed the dovecot cache file. Mail is showing on webmail, but its blank, no subject, no body. The logs show below errors:
   
   May 16 18:24:01 servername dovecot: imap([email protected])<15198><QKeGbMOlWJ4AAAAAAAAAAAAAAAAAAAAB>: Error: Mailbox INBOX: UID=132792: read(/var/vmail/domain.com/user/Maildir/cur/1589559226.M3735P32435.servername.xxxxxx.net,S=31719,W=32233:2,) failed: Cached message size larger than expected (31719 > 4702, box=INBOX, UID=132792)
   

Please help us find a solution to the above, as without email users working properly, it won't be possible to migrate anything over.

Thanks

 

From the looks it seems the mails in the Maildir are compressed, and dovecot isn't configured to read them properly. Making any change in /etc/dovecot/conf.d directory is not getting loaded. Does the config load from somewhere else ?

 

I have sent a mail to the migration support email.