Greetings,
Shouldn't be too hard to figure out. Take each error one at a time and confirm:
-Network connectivity
-Incorrect email address, SMTP server, ports or credentials
-Your Firewall or ISP is blocking traffic
#752
Cause 1
The server is not functioning. The network is not connected.
Remedy
Check that the SMTP server is operating properly. Check the status of the network.
Cause 2
The SMTP server name for the e-mail or I-fax is not correct. Alternatively, the domain name or e-mail address may not be set.
Remedy
Check the SMTP Server Name, Domain Name, and E-Mail Address in Communication Settings. (See "Common Communication Settings for E-Mail/I-Fax.")
#753
Cause
A TCP/IP error (Socket or Select error, etc.) occurred when sending an e-mail or sending a fax from the Remote Fax client machine.
Remedy
Check that the network cables and connectors are properly connected. If the machine still does not operate normally, turn the main power OFF, and then back ON. (See "Main Power and Energy Saver Key.")
#806
Cause 1
An incorrect user name or password was specified for the sending of a file to a file server.
Remedy
Change the user name or password.
Cause 2
An incorrect destination was specified for the sending of an e-mail message or I-fax.
Remedy
Check the e-mail or I-fax address.