I use a local IMAP Server (dovecot) as my mail archive. I’ve used <F1> in Mail app to export some mail folders to EF and in parallel used the mutt mail client to export mbox files from the IMAP archive which I dropped into FE.
Oddly enough neither the size of the resulting mbox files nor the number of exported mails are equal in all cases:
Size Archive_Name 14M 2000 14M 2000-mutt 14M 2001 46M 2001-mutt 114M 2002 113M 2002-mutt 149M 2003 149M 2003-mutt 226M 2004 252M 2004-mutt 324M 2005 325M 2005-mutt
Has anyone else seen anything like this?