365 and outlook backups

We have a few clients that are law firms. They would like to keep there email for just about ever, well ten years or more. They are using outlook and outlook in office 365. There PST files are getting very large, very… What is the best way to manage this. I am sure it is not a new problem.

Also if we switch the, to Google office? Any better ideas?

O365 offers archiving, I would look into that.

We backup our 365 tenants with Solarwinds. We get users to purge down their mailbox or increase their licence to provide them with more space in 365 when needed. Haven’t run into anyone hitting the 100GB limit. I don’t know exactly what the current archiving policy is. I believe at one point in time it still counted towards your 50GB limit, not sure if that still applies today.

For this sort of situation, we use MailStore. Its an on-prem archive solution (or private DC).
What I like about it is it can purge email from the users mailbox after the archive runs.
So for example, we often set it to archive ALL email and then purge email older than say 5 years. This keeps the users OST files / mailbox under control.

Veeam offers a specific backup product for O365 very comprehensive. https://veeam.com