I tried once again to send them an email and the following message is what was returned to me.
This is an automatically generated Delivery Status Notification
Delivery to the following recipient failed permanently: Link hidden: Login to view
Technical details of permanent failure:
PERM_FAILURE: Gmail tried to deliver your message, but it was rejected by the recipient domain. The error that the other server returned was: 550 550 5.1.1 ... User unknown. We recommend contacting the other email provider for further information about the cause of this error. Thanks for your continued support. (state 14)
Given the status of their emails, it appears that this company is no longer in business.
I just thought you should know, Jimmy, so you could remove them from the list of suppliers.