Distributing Addin

Oct 30, 2013 at 9:44 AM
I have signed my add-in using a key generated in office (ends in .pfx).

I have tried to distribute it to my customers, but they are all getting this warning message:
"Warning: the digital signature is valid, but the signature is from a whom you have not yet chosen to trust". It shows three buttons with the only one enabled being 'Leave this addin disabled" - therefore they are unable to use it !!!

If I were to send out addins in future, is the only way to avoid this problem is to buy a commercial certificate??