Version 6.1.1 has the following improvements:

Feature 4580: Added support for Mail on Monterey.
Bug 4571: Fixed an error "PDF can't be created" when emails had a space at the end of the subject on Dropbox.
Bug 4572: Fixed a hard crash when archiving emails with MailTags to PDF.
Bug 4573: Mailboxes containing the "Orphaned mailbox" are now excluded from archiving.
Bug 4577/4581: Fixed some problems with the index for the Pro version.
Bug 4588: Clicking outside of the error description in the Error Report window no longer removes the already entered text.