Yes, MX will allow you to use a single email address and connect with multiple MX customers.

Each customers' data is kept separate from each other, with only your email address being common.
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If your email address is changing, please speak to your MX administrators who will advise on the best way to handle this. Please do not just go ahead and change your email address.

If a MX customer is using the wrong email address, contact that customer either through your business contact, or, contact one of the administrators and ask them to remove the wrong email address and add the correct one.

Review the list of MX administrators under Settings => Account information.