Stop the first letter of a second sentence from being uppercase

[Phyllis Richford]

When my boss is typing an e-mail when he goes to the second sentence the first
letter always becomes uppercase and he wants to change that.

 

[F. H. Muffman]

When my boss is typing an e-mail when he goes to the second sentence the
first
letter always becomes uppercase and he wants to change that.

Why wouldn't you want the second sentence to be properly cased? otherwise,
it looks sloppy, like the beginning of this one.

Now, if instead you mean second *line* which is not the same thing, either
turn off the auto-correct option, or don't hit the Enter key to go to a new
line and let Outlook wrap it for you.