MailStore works really well for ensuring there's a compliance copy of every message sent and received, as well as reducing live mailbox sizes by archiving out everything older than whatever time period you specify.

It's highly customisable, and the powerful searching means that you have no trouble finding archived messages when needed.

It can be up and running pretty quickly, depending on your mail platform, although there's a lot of scope for fine-tuning the setup, and it's worth bearing in mind considerations around server and archive maintenance/management (mainly ensuring you have reporting to confirm it's all working, and that your archive is properly backed up somewhere).

Once you've invested a bit time in getting the setup correct and optimised, however, it's pretty much just a case of install and forget.

From an end-user point of view, searching is easy, and users get used to it pretty quickly. Review collected by and hosted on G2.com.

Setup for archiving Microsoft 365 is a bit more complex, but mainly due to integrating with Modern Authentication, and the documentation for this is pretty good.

It's a shame that there are still no Mac or mobile clients, however; Windows users benefit from both a standalone Client application and an Outlook plug-in, but Mac and mobile users have to stick with just the web-based interface. Review collected by and hosted on G2.com.