Sure. When composing the e-mail, take a look at the second tab on the left (under the recipients tab) where you'll find the 'Queue, Calendar and History options' button. Press that and follow the on-screen options/explanations.
That'll queue it in the outbox. You'll need to make sure you have auto e-mail send/retrieve turned on for it to go once the appointed time arrives, however...
Plus the setting in the Retrieval tab that reads: "Send queued messages".
Create your email as you normally would.
Just below the <Send> button at upper left, click the 2nd vertical icon (Options).
In the 2nd horizontal options block at upper right, click the <Queue, Calendar and History options> grey button.
In the drop down box, set the Date and Time for delivery (and other details for this email), then click okay.
Just to the right of the <Send> button at upper left, click the <Queue> button.
Your email will be placed and stay in you email Outbox and will be sent when your designated Date/Time occurs, or at the next point your system is on and GoldMine is open.
The only thing I don't like about queuing emails is that you have to keep GoldMine opened for the scheduled time for the email to be sent, which is fine if you're going to send it while you are logged in - otherwise you have to keep your GoldMine opened all night.
The other thing is that you have to set the option to "retrieve mail every X number of minutes". Roy, if you're ok with that, then what everyone above has suggested is a good thing.
I was also going to suggest a small Automated Process, but realized that the server agent would need to be on or someone would have to run the processes. That wouldn't work either unless they already had Automated Processes running with a server agent - then it would work.
A good feature to look at for future enhancements.