form submit -one of the specified recipients not resolvable

Hi all I am helping a local business with their IT issues and while I can help with most things this has me stumped. why? because it seems everyone else other that this business seems to be working.

I have looked at google all morning and I see a number of similar issues but most of them see to be around the creation of the form and coding. I have this form from the mother company we need to fill out and then submit and it seems we are the only ones having issues? I am stumped.

Seems some people talk about the issues could be,

the email client? we are using outlook

32 or 64 bit? I know the PC is 64 bit

Any help you can throw my way would be greatful thank you all