CiviMail Links in Test Mailings Not Consistent

I do the following in 2.2.5:

Follow CiviMail Wizard up to the point where I can send a test mailing.
Send a test mailing to me.
Links work fine.
Send another test mailing to another staff person.
Links don't work. Instead they just redirect to our site home page.

But if I send to a group instead of doing 2 individual test emails, links work fine. It is only a problem upon sending 2 separate test emails to 2 separate email addresses.