Select the contacts you want to email, go to the Actions item in the toolbar, and select "Email". That will address an email to all the selected contacts (though it will be a single email with all the addresses, not individual emails; I'm not sure exactly what you need).

Just FYI, it's unlikely that there will be any further enhancements to NUDC 5.x, particularly not feature additions. The product is being replaced by an entirely new version, codenamed Nighthawk. You'll probably want to make any suggestions for new features in the Nighthawk Suggestions forum so that John, et. al. are aware of your need.

Regards.
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Dave Sawyer
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iMac 24 2.8GHz Mac OS X 10.6.2
PowerMac G5 2GHz DP Mac OS X 10.5.8
Windows XP, Vista and Windows 7