how can I mark paper edge to exactly fold paper to fit DL envelope

[graygle]

I have noticed a small line on the side of letters I have received which
enables a sheet of A4 paper to be exactly folded into three on the mark. Does
this have to be set up in a template ? Or how do you do it ? On Microsoft
office or word

 

[Suzanne S. Barnhill]

The easiest way to do it is with drawing lines, which can be inserted in
roughly the right position and then positioned more exactly using the Layout
| Advanced settings in Format | AutoShape. But note that you will not be
able to print them all the way to the edge unless your printer is capable of
printing to the edge of the paper.