Why do we see error message during receiving mails via sendmail?

Resolution

• Use following two lines in sendmail.mc :

define(`confTO_DATABLOCK', `2h')dnl 
define(`confTO_DATAFINAL', `2h')dnl

• Execute following commands :

$m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf
$service sendmail restart

• In addition following directives can be used :

onfTO_INITIAL   Timeout.initial [5m] The timeout waiting for a response on the initial connect.
confTO_CONNECT  Timeout.connect [0] The timeout waiting for an initial connect() to complete. This can only shorten connection timeouts; the kernel silently enforces an absolute maximum (which varies depending on the system).
confTO_ICONNECT Timeout.iconnect    [undefined] Like Timeout.connect, but applies only to the very first attempt to connect to a host in a message. This allows a single very fast pass followed by more careful delivery attempts in the future.
confTO_ACONNECT Timeout.aconnect    [0] The overall timeout waiting for all connection for a single delivery attempt to succeed. If 0, no overall limit is applied.


confTO_HELO Timeout.helo    [5m] The timeout waiting for a response to a HELO or EHLO command.
confTO_MAIL Timeout.mail    [10m] The timeout waiting for a response to the MAIL command.
confTO_RCPT Timeout.rcpt    [1h] The timeout waiting for a response to the RCPT command.
confTO_DATAINIT Timeout.datainit    [5m] The timeout waiting for a 354 response from the DATA command.
confTO_DATABLOCK    Timeout.datablock   [1h] The timeout waiting for a block during DATA phase.
confTO_DATAFINAL    Timeout.datafinal   [1h] The timeout waiting for a response to the final "." that terminates a message.