Mail archive software recommendations?

Before upgrading to Catalina from Mojave, I want to archive a large number of POP3 email messages currrently located in On My Mac, and am trying to decide between EagleFiler and MailSteward.

One thing I like about EagleFiler is that it apparently preserves message status. (Not sure about MailSteward though.)

MailSteward says it can handle multiple databases up to about 250,000 messages in each (I will need several) but I can’t tell whether EagleFiler is that robust.

I would be grateful for any comments or recommendations.

Thank you,