Unable to set up an account with my company email address

I have attempted to set up a new account using one of our company emails.  I have set up three other accounts that are similar names but have sequential numbers assigned to each of them The first account starts with the name Rxxxx-1@mycompanyname.tv however this first account doesn't seem to send me an activation email.  The other accounts increase in numbers and there is no issue and their activation went through.  Its really important that this first account has the #1 in it.  Any help would be appreciated to solve this issue.