Underlining may depend on the features offered by the website. Are you creating/editing an email on a popular webmail site such as Yahoo Mail, Outlook, or Gmail?

I am trying to underline one letter in an e-mail address in my contacts on my Yahoo Mail. In addition, I would like to know how to underline words on documents written through Open Office. Your help will be greatly appreciated.

This could be different between Windows and Mac, but let's give it a try.

On Windows, Yahoo Mail! will underline selected words or characters if you press Ctrl+u on the keyboard. On Mac, does Command+u (or Ctrl+u) do anything useful to the selected words or characters?

If not, how about a bookmarklet? That's a script you save as a bookmark (either on the Bookmarks toolbar or menu). You run it by clicking it.

The script is simply this (all one line):

javascript:void(document.execCommand("underline",false,null));

To install it, first select and copy it.

Then right-click on the Bookmarks Toolbar (or Mac equivalent!) in the vicinity of where you want the button and choose New Bookmark.

Click in the Location box and paste the script (Command+v)

Click in the Name box and type Underline or the name of your choice

Then click Add Bookmark

Now, with text selected in the compose area, clicking the button should toggle underlining on and off.

Does that work on Mac?

Regarding Open Office, do you mean in the stand-alone program or is there now a version that runs inside Firefox?

In the stand-alone "Writer" program there may be a U on the toolbar or a keyboard shortcut that works there as well. (This really is not the best site for answering that question.)