Saw a tweet from Shaun the other day about a promising addon to catch spam registrations.. perhaps that can help you?
http://twitter.com/#!/splittingred/status/30391651851567104
http://modxcms.com/extras/package/803
If you want an approval workflow, you could set up a "limited" or "awaiting approval" user group, and manually update the users in that group when they are approved.
To make it easier, you could have a plugin email you on registration (
OnUserSave + modMail), and a CMP which lists all users with a certain user group and a button to change it to another one. I don’t think it’s particularly hard to implement, but will take some work.
There’s also a built in "active" field which could possibly be used for a workflow like this, but not quite sure yet how it is being dealt with currently.
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If developing this yourself is too much / not your cup of tea / nobody else has free time to develop this, and you would be willing to spend some money on getting this developed for Revolution (and released to the public as an addon), don’t hesitate to send me an email for a quote.
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