Importing OLM files to an IMAP account is simple with SysInfo OLM Converter. Just load your Mac Outlook OLM files into the program, choose IMAP as the destination, and pick the folders to migrate. You can skip attachments if needed or apply filters to move only selective emails. With one click on Convert, your complete mailbox will be uploaded to the IMAP server without losing any data, keeping everything organized in the same folder hierarchy.
Read more: https://www.sysinfotools.com/blog/import-olm-to-imap-server/