But my site is set for english.
I have been trying for several days to figure out why and how to fix it but I am out of ideas. Can someone help me?

I can't fix your problem, but I can help you get a response from someone who can.

First, is this a new problem that has suddenly appeared on a site that was fine before? - we would all like to know if this is something new.

What version of the system are you running? - very significant.

What have you done to try to fix this problem? - saves people from wasting time telling you things that you have already done.

A re-install is a standard first step.

With more information, your post may get more attention from the users.

Good luck.

check the language/english/mail_template/register.tpl file (well the mail templates files) to make sure they are in english.

and answers to GPboarder's questions would also help.

It's a fresh install.
My XOOPS is 2.16 but last night I saw that 2.18 is available so I have it downloaded so I can upgrade this weekend.
There is only one version of the module that I am aware of.

The tpl files are in English. It took me awhile to find them but I knew that was the first place to look. So I THINK that somewhere in whatever file controls the sending of the email it is calling the wrong language file. But that's pretty much the end of my abilities to fix this. I don't know the file structure of XOOPS well enough at this point to know where to look. I was in the adminactivate.tpl (if I remember correctly) and tried to adjust the path to make sure it was going to the english folder but that did not work.

Basically I've just been poking through files trying to find something that LOOKS like it might be set wrong.

Also, I know the password recovery emails and the notification of module updates emails are being sent in english.

Okay it's fixed after upgrading to 2.18 and then copying the module files over again.