Here's a couple things I would try
bye for now.
I see no one has responded to this post yet. So, at this point I would recommend contacting your local Xerox Support Department to speak with a Product Specialist for more assistance. Please call 1-800-821-2797.
I have 2 Xerox machines on a customers network. They have an IT Company or Department. All the machines are working but 3. They are all using the same settings. there is 1 C405 and 2 7830s involved. We have upgraded the software to the newest versions. Tried sending to various address from the address book and manually keyed in. They are using a relay with MS Exchange. 2 or in one office and 1 is in another. I am running into a loss as to what to do. I am trying Appriver today or possibly even a google account to just see if it will send.