[mrtombomb]

Is there any way to import a mail merge contact list on to an envelope to save me manually inputting each address from my contact list onto the envelope each time?

[spacesurfer]

Yes. Right click on toolbar and select the Mail Merge toolbar to display the mail merge toolbar. Then click on the first button of the toolbar (the tooltip should say Main Document setup). Then select "Envelope". You should see a dialog to select the size of the envelope.

After that, you should know what to do.

Alternative solution you may want to think about is printing your addresses on labels, then sticking them on the envelopes. This might be better that printing directly on envelopes.