A client has provided us with an excel spreadsheet of around 10,000 email addresses, names and addresses. They were taken from a CRM used previously.

I've been asked to "clean" up this database - such as check for invalid addresses - (email format, existing mailboxes etc).

I've done a bit of Googling and came up with a few "Email List Cleaning Services". Here is one such company.

Now my question is - does anyone have any experience with this kind of service, and is it a legitimate service?

Alternatively, what are my options for "cleaning" this list?

I ask as MailChimp, our preferred email marketing tool, will terminate account access if a certain percentage of emails bounce, (and I imagine similar e-shot services operate on the same basis), to comply with anti-spam regulations etc.

This is a legitimate cause, although it may sound quite the contrary.