Sextortion emails

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Issue abstract: I am secretary for a small professional organisation with several email addresses/postboxes to allow members to access varied information on different subjects. I’ve been swamped with ‘extortion’ emails and, normally I would delete them and clean out the bin. However, it appears the source email address is one of our own, it changes every few days and I’m concerned that one of the accounts is hacked. I’ve changed the PW on the main email a/c. I’ve done a Norton scan and nothing has been picked up. Only other things is I’ve had a few notifications that associated email addresses have been picked up in the dark web, but the passwords are years out of date. Any info to help ease my mind, or how to deal with is greatly appreciated.

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