Unable to send invitations anymore

Hi, 

I've recently signed up to Box and have had some issues with sending out invitations.

I had invited a particular external collaborator several times to view and edit a document, however it appears his invite was getting caught in their mail systems filter.

Now that the filter accepts invites from box, I'm unable to resend the request because of an unknown error.

Could someone please advise?

Regards,

Chris