Warn your existing accounts, give the usual cautions against social engineering phishing attacks to gain their credentials. If accounts are valuable, give each an account USB U2F security key, if capable of that kind of security. Adds $10 to your costs, but might be cheaper. Or you can use an Android or Apple security App, like gmail does. Might aggravate clients. It is a balance.
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Warn your existing accounts, give the usual cautions against social engineering phishing attacks to gain their credentials. If accounts are valuable, give each an account USB U2F security key, if capable of that kind of security. Adds $10 to your costs, but might be cheaper. Or you can use an Android or Apple security App, like gmail does. Might aggravate clients. It is a balance.
U2F sells here
https://www.amazon.com/HyperFido-K5-FIDO-U2F-Security/dp/B00...