There is an incorrect value for the INACTIVE statement in hlq.SMTP.CONFIG. The INACTIVE statement specifies the number of seconds of inactivity after which SMTP considers the connection to be dead. The connection is then closed. The correct range for the INACTIVE statement is between 0 and 86 400 seconds. SMTP uses 180 for the INACTIVE statement's value. For more information on the INACTIVE statement, see the z/OS Communications Server: IP Configuration Reference.