The best solution available to export IMAP emails to MBOX file format is eSoftTools IMAP Backup & Migration software, it is designed in such a way that it can be used by both novices and professionals without losing any data. Moreover, it also has the capability to extract IMAP account emails to PST, MSG, HTML, MHTML, EML, EMLX and other file formats. To know more features, try it with a free demo without any delay.
Read more- Export IMAP Emails to MBOX File Format
Read more- Export IMAP Emails to MBOX File Format