Envelope Printer was developed for #10 Envelopes. However, the program can print on larger envelopes with the addressing still conforming to #10 envelopes so that the return address and the addressee addresses will both appear more centered on the envelope.
For printing smaller envelopes you would simply increase the values for the Vertical and Horizontal locations.
I was asked for some assistance for 3 5/8" x 6 1/2" envelopes and these are the values I came up with.
[Image not available: 3.625in x 6.5in Envelope Settings.jpg]
I will post other values as needed or as users submit their findings.