Quick envelope question

When printing the envelopes yourself (or even handwriting them) are you keeping them centered completely or justifying to the left?

(The post office says it reads easier off center to the right and closer to the bottom)

Right now my printer is set to slightly off center and all the lines justified left, but I can't help but think should I change it to the middle and have the text centered?

Thanks in advance.

I did mine centered. My envelopes were 4X9 (basically, regular letter envelope size), with the return address on the back, and I liked how it looked.

Honestly, I did not think about or care what the PO can read better.