IPT invite trouble

Anyone havin trouble sending invites to this tracker ? I 'v sent three out this weekend and people are not getting their comfirm e-mail . :huh:

I know that their trackers have up and down several times last couple days

Ya thanks gerp for the reply ,I was wondering if it was something the invitees had done wrong or just the site . I'm guessing its the tracker . The sad part is the open window is what two days,then the invite is lost ?