We all have our ways of doing things. Some of us have no ways of doing some things because we're not sure how to do them. Well, if that's how you feel about spacing on envelope addressing, might I offer up my way of doing it? When addressing white envelopes, I print these guidelines, trim to size, and slide it into my envelope. It is easiest to slide them in when printed on a white card stock - 65#-80# - vs. a flimsy printer paper sheet.
There are two sets of guides in the PDF - one with 55 degree slant lines, and one without. You can rescale them when printing to better fit the scale of your envelope. This particular scale I prefer for an A7 envelope. You'll want to adjust where you cut on the horizontal depending if your envelope is going to require three or four address lines (or more). For example, on an A7 envelope size, using this scale, I'll start two lines higher for a four-line envelope than a three-line envelope, so my cut will actually be two lines lower than where I've cut for my three-line template.
The letter placement above is exactly how I'd space it in the envelope. The bottom space of the four-space section is my x-height. There is one space above the capital letters and ascenders to give each line some breathing room, but without looking too departed.
When using my laser with a darker colored or lined envelope, I use the full size sheet and align the bottom of envelope to a specified line, and make sure the laser is aligned to the bolder printed lines on the sheet. Shift your envelope up or laser down and you move down each line of the address.
As always, feel free to ask questions below!
Ink on, B