Canon imageCLASS 2300 Reference Manual page 181

TRANSMITTING...
Cause 1
Remedy
Cause 2
Remedy
TX LIMIT REACHED
Cause
Remedy
WRONG PAPER SIZE SETTING
Cause
7
Remedy
7-26 List of Error Messages
During the current transmission, your machine may have tried to send a
document identified from the list of documents in memory.
Resend the document when transmission of the first document is complete.
You tried to send a document using direct sending while sending another
document from memory.
Wait until the transmission from memory is complete. Then resend the
document using direct sending.
Sending has been restricted.
Set <RESTRICT TX> from the DEPT. ID MANAGEMENT menu to 'OFF'. (See
"Restrictions Using Department ID Management," on p. 5-17.)
It is possible that the paper size detected automatically by the paper drawer
does not match the actual paper size. Another possibility is that the paper
size selected for the stack bypass in the USE STACK BYPASS menu does
not match the paper size actually set on the stack bypass.
Make sure the actual paper size matches the selected paper size. Set the
correct paper size and open the front cover, then close it.