Configure senmail on CentOS

Configure Sendmail on CnetOS

1. Locate and edit the sendmail.mc file at /etc/mail

Comment out these lines from the default config by removing the dnl from in front of the line.

define(`confTO_QUEUEWARN', `4h')dnl

define(`confTO_QUEUERETURN', `5d')dnl

FEATURE(delay_checks)dnl

define(`confSMTP_LOGIN_MSG', `$j server ready at $b')dnl

I comment this line by adding the dnl in front of the line:

dnl DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA')dnl

and add the following line in it’s place to allow the server to accept connections from outside, so in the end it looks like this:

DAEMON_OPTIONS(`Port=smtp, Name=MTA')dnl

2. Create the sendmail.cf file

From the /etc/mail directory, you can backup the current and then create the new sendmail.cf like this:

cp sendmail.cf sendmail.cf_`date +%m%d%y_%H%M%S`

m4 sendmail.mc > sendmail.cf

You can simply view the m4 output by doing this:

m4 sendmail.mc

3. Configure the /etc/mail/local-host-names file

add the desired domain name into this list: NCWVMPDB.***.gov

4. Configure the /etc/mail/virtusertable file to receive emails

admin@ NCWVMPDB.***.gov        real_email_address

5. Build the database or hash of the file by using the following command

makemap hash virtusertable < virtusertable

6. start/restart the mail server

/etc/init.d/sendmail restart

Q: How to install sendmail

A: $ sudo yum install sendmail

Q: cannot open `/usr/share/sendmail-cf/m4/cf.m4'

A: You need to install the sendmail-cf package. $ sudo yum install sendmail-cf

Q: NONE:0: m4: ERROR: end of file in argument list while you were using the m4 sendmail.mc > sendmail.cf

A: check the quotations in sendmail.mc file, particularly the sentence you added, to make sure that the quotation is ` and ‘, since m4 expects back-tick - tick quoting (`xxx')