Teach me about: sendmail

[Kareeser]

As I've discovered lately, "sendmail", while popular, is quite difficult to configure and/or customize. Ideally, I'd like to host an email relay or server, but one step at a time!

My extent of knowledge on MTAs and sending mail is thus:

sudo apt-get install sendmail

That little magical command was enough to download, install, and configure sendmail, so my web applications could send emails across the globe.

However, there doesn't seem to be any way to send mail TO the server in question. That is, if I send an email to kareeser@mydomain.com (mydomain.com being an example, of course), the sender (in this case, GMail) reports it as sent, but it never arrives in my local mailbox on /var/mail. So, I'm guessing that there needs to be some sort of configuring to be done on the server side so I can receive email?

Be blunt! If the answer is "sendmail is exactly what it says, it SENDS MAIL, you dolt!", then tell me!

I've been looking at other MTAs, like exim4... are they easy to set up?

Teach a newbie sysadmin!

[mobj]

a simple google search revealed those:

http://www.elandsys.com/resources/sendmail/
http://www.harker.com/sendmail/accept.local.domain.html


HTH

[E_K]

dont bother with sendmail, look into, postfix and dovecot.

If your going to do something do it properyly

just google.... "ubuntu how to 'whatever'"

check if the ports you want to use are open from your ISP, this is VERY annoying, and you might have to use a deflector service such as the one available from no-ip and run your servers from a non standard port.

Even then you may have to use your ISP as your SMTP server

[hictio]

Sendmail by default does not listen on the network interface, it only does on the loopback one (that's one of the reasons why you have been able to send emails from your box)
Since current Sendmail versions only listen for connections on the loopback interface, you'll have to edit the sendmail.mc configuration file, and add the IP address of the ethernet device connected to the network (or remove all the entries, and allow Sendmail to listen on every single one)
Here you can read a very good tutorial on how to it, is it based on Red Hat, but except for the RPM stuff, it'll work

Configuring Linux Mail Servers

[windependence]

Almost no one uses sendmail anymore. Postfix is a drop in replacement for sendmail and is probably the most popular MTA out there today on Unix.

If you are looking into building a mail server, you may be surprised to learn that it's not a beginner's project. A full mail server requires an MTA and a POP or IMAP server to send and receive e-mail. Many of us who just want to run our own mail server use a bundled package such as Zimbra or Citadel. these packages install all you need in one convenient package and are much easier to configure.

-Tim

[Bachstelze]

Almost no one uses sendmail anymore.

http://www.securityspace.com/s_surve.../mxsurvey.html

[windependence]

http://www.securityspace.com/s_surve.../mxsurvey.html

I knew someone was going to do it. Why is it necessary to try to dispute something that is helpful to people, especially n00bs? Even with all the years of experience I have with Linux/Unix, I still don't want to, nor do I know anything about configuring sendmail. Not only that, I won't even get into the security problems with it.

Do you really think it's useful to encourage users (especially new users) to use something extremely difficult to configure and insecure?

I'm not about to get into a ******* match with you on what MTA is most popular as it is irrelevant to the OP's question but it should be pointed out that the survey you quoted is certainly not all inclusive or even necessarily a significant sample of the total mail servers in use. Furthermore, banners are not an accurate indicator for what software is being used, not to mention the survey is over 2 years old.

Now let's help the user with his problem shall we?

-Tim

[Bachstelze]

I knew someone was going to do it. Why is it necessary to try to dispute something that is helpful to people, especially n00bs? Even with all the years of experience I have with Linux/Unix, I still don't want to, nor do I know anything about configuring sendmail. Not only that, I won't even get into the security problems with it.

Do you really think it's useful to encourage users (especially new users) to use something extremely difficult to configure and insecure?

I'm not about to get into a ******* match with you on what MTA is most popular as it is irrelevant to the OP's question but it should be pointed out that the survey you quoted is certainly not all inclusive or even necessarily a significant sample of the total mail servers in use. Furthermore, banners are not an accurate indicator for what software is being used, not to mention the survey is over 2 years old.

Way to not go into a ******* match! You said something that was blatantly wrong, I corrected it. Period. Now until the OP tells us which MTA he chose, we can't really help him about configuring it.

My recommendation: sendmail. I'm running it on two mail servers, it's not nearly as difficult to configure as many people make it look like. As for being "insecure", I shall remind you that, to give just one example, OpenBSD uses it as its default MTA, and the OpenBSD people do not exactly have a reputation for including "insecure" software in the base system.

[joeydan1]

hihi
i'm the first time to use the sendmail software, now have several questions as below, hope can be answer, thanks.

when i typed the command would show this error

[root@localhost]# service sendmail start
Starting sendmail: sendmail: fatal: open /etc/postfix/main.cf: No such file or directory

i'm installed the postfix before, but already unstall it by "rpm -e postfix", i don't know why it need the postfix/main.cf file when starting the sendmail, anyone know the reason?

daniel~

[hictio]

hihi
i'm the first time to use the sendmail software, now have several questions as below, hope can be answer, thanks.

when i typed the command would show this error

[root@localhost]# service sendmail start
Starting sendmail: sendmail: fatal: open /etc/postfix/main.cf: No such file or directory

i'm installed the postfix before, but already unstall it by "rpm -e postfix", i don't know why it need the postfix/main.cf file when starting the sendmail, anyone know the reason?

daniel~

rpm? What Linux distribution are you using? Red Hat or CentOS?