Users not receiving 6 digit security code via email

I've setup a few dozen users for remote access and I'm having problems with several of them not receiving the 6 digit security code in their email since it detects they're using a new PC to remote in with. I walked through the steps with them in the office, and now that they're at home it doesn't like the new sign in location. Ergo, it emails them the 6 digit security code that never arrives. I've looked in spam/junk and everywhere I can think of, nothing. If this is an issue with LogMeIn server loads right now, that's fine. I just need an answer and an alternative way to get them access.