Former client lists our office address as their own

Out of the blue - no permission, no heads up, nothing.

We are getting all of their personal and business mail. This includes bills and other items that look important.

I think they currently live overseas.

How do I handle this? Can I email them:

Hello - our office has been receiving mail in both of your names.

I'm very sorry, but receiving, storing, opening, acting as an address/agent for you, or otherwise managing your personal or business mail is not a service that we are able to provide.

We will be returning these items to the post office with a note that says, "not at this address".

Please immediately correct this issue and remove our address from your correspondence for all senders.

Thank you,...

I agree with you. However, if it's a good client that you intend on keeping, I would probably FedEx the items to the client, not return them to the post office. Returning them to the post office probably means they're going to disappear into a black hole.

Maybe something like: Let them know that you're going to hold and accumulate all mail for 30 days (to account for lag time), then FedEx everything received. Anything that arrives after that will be returned to the post office with a note that says "not at this address".

There are companies that provide mail receipt and processing services. One gets a US based mailing address. Once the mail arrives, it is opened, scanned in, uploaded to portal, and a notification is sent. Many of these companies also have an option to FedEx/UPS the original if necessary. A good many of my expat clients use said companies.

I would inform client that such companies exist and direct them there.

https://www.postscanmail.com/

Looks like a pretty good one, but there are many out there.

If they were my clients, I would make an attempt to call them first and if that fails then I will return to sender.

I too get mail for other people that I have no idea who they are and I have a Return To Sender stamp that I use!