I am trying to set up the most simple email server on an Amazon Linux 2 host for simple outbound mail (e.g. sending system messages). Following instructions on the net, I have installed mailx and sendmail. I am not committed to either package, I just want a simple setup with a minimal footprint. I have no problem switching to postfix if that is a better solution.
For configuration I have made the following changes.
/etc/sysconfig/sendmail:
DAEMON=no
/etc/mail/submit.cf (hostname obfuscated):
D{MTAHost}smtp.******.com
This works fine, and I am able to receive mail that is sent from the system.
There is a wrinkle. The anacron process is sending mail to the root account. However, rather than the mail being kept internal to the system it is being sent to the SMTP server. The SMTP server sends the message back to my host, which doesn't accept mail, and a loop is created when an 'undeliverable' message is send back to root on the host that doesn't accept mail.
How can I configure my system so email to root stays local and is not sent to the SMTP server? Any other 'best practices' suggestions would be welcome as well. And again, if switching to postfix is better, I am willing to do so (but will need configuration guidance).
I have installed sendmail on Centos 7 and setup relay server using SMART_HOST.
But sendmail is not using my relay server when sending email, it keeps using localhost.
Can anyone help me to solve this problem?
Sendmail-8.12+ by default relays messages submitted locally to local main sendmail daemon running at 127.0.0.1:25. It does it as a security precaution to avoid installation as set root uid.
Have you checked sendmail log files? They should show where main local sendmail daemon relays messages to non local email addresses.
Documentation: SECURITY file in sendmail distribution
I found the answer myself.
The mistake was with LOCAL_DOMAIN.
I had put my local domain (which was used for mail server and email address) here.
And all of my emails were being handled as local emails.
Local emails were meant for excluding from relay, lol.
How do i send mail on my ubuntu system. I need to send mail in my ruby on rails application but can't test, because mail isn't being sent. What do i need to do on my system. (now testing this app is making me realize why mail wasn't being sent through that Evolution thing i have installed)
The Evolution thing is an MUA (Mail User Agent) like Outlook, Thunderbird, or any number of programs intended for user to read and create email messages. Your program is also a limited MUA (likely creation only).
You need to send your e-mail to an MTA (Mail Transfer Agent). If you configure the return address correctly, you may be able to use the same MTA that you connect to with Evolution. In this case the SMTP server used to send email. If you are using one of the e-mail libraries you should be able to specify the SMTP server name as well as a user-id and password if required.
Many packages require an MTA so you may have Postfix, Exim4, or Sendmail already installed. Check for programs listening on port 25. If so you can use localhost as your SMTP server. If you need to send email other systems you may need to configure your MTA as a satellite to your ISPs server which will relay your message out to the Internet.
I'd like to test to see if I can send email unauthenticated from an smtp server from my red hat box.
If I want to send a test email from command-line, I would do something like this:
mail -s Test addr#domain.com < /dev/null
How do I specify an SMTP server to send the mail through?
AFAIK you can't tell the built in 'mail' application which SMTP server to use - it simply uses sendmail on the local system.
You might want to grab the 'nail' rpm and use that instead, as then you can put 'set smtp=serveraddress' into /etc/mail.rc
You could try putting that in now, but it doesn't work on my CentOS 5.3 system.
This is a problem I'm sure is easy to fix, but I've been banging my head on it all day.
I'm developing a new web site for a client. The web site resides at (this is an example) website.com. I have a PHP form script to email visitors' requests to requests#website.com.
When I coded this on a staging server on a different domain, all worked fine. When I moved it to website.com, the mail messages never arrived. The web server is on a virtual host with a major ISP.
Here's what I've learned since then: My client's mail server is Microsoft Exchange on a box physically in their office. Whenever someone on the outside world emails requests#website.com, the mail arrives. But if the web server sends to the same email address, it fails every time. This is not a PHP problem. I secure shell in to the web server and have tested this both with sendmail and the UNIX mail application. I've also tested it by emailing various email accounts from the shell. I can email myself, for example, just nobody at the website.com domain.
In short, when I'm logged in to website.com, mail to requests#website.com, user#website.com, another_user#website.com all fail. All other addresses work fine. What I've discovered is those dropped emails are routed to the web server's "catchall" account where they sit in its inbox.
I've done an MX lookup on website.com. The MX record points to mailsec.website.com. I can telnet to mailsec.website.com port 25 and see the SMTP server.
It appears to me that website.com isn't doing an MX lookup when it's sending mail to requests#website.com. My theory is that it recognizes the domain as local, sees that there's no "requests" user account to deliver it to, and drops the mail into the catchall account. What I want is to force sendmail to do the MX lookup and send the message on to the Exchange server. I'm at wit's end here. I can't figure out how to do this.
For that matter, I may be way off base here and have misdiagnosed this entirely. Internet mail and MX has always seemed a black art to me, and my ignorance is certainly showing in this question.
I think the problem is that sendmail (your process) is talking to the local sendmail daemon. The local sendmail daemon thinks that because it is website.com, it should know how to deliver the email. Unfortunately, the actual address in the to field does not exist on the web server and thus it dumps it in the "catchall" mail box. You should talk to your ISP and have them update their sendmail configuration so that mail addressed to ...#website.com gets forward to the mail exchanger instead of being handled locally.
Sendmail by default guesses list of local email domains.
It can be turned off using the following line in your sendmail.mc file:
define(`confDONT_PROBE_INTERFACES',`True')
As root list local email domains before and after the change using:
echo '$=w' | sendmail -Am -bt
You will see which domains should be added "manually" to (usually) /etc/mail/local-host-names file after disabling auto-guessing.
After changing sendmail.mc:
Generate/compile new sendmail.cf file
Restart sendmail daemon (or send HUP signal)
tvanfosson basically has it, but as a temporary workaround, you should be able to change your script so that it mails 'user#mailsec.website.com', and then the mail will get delivered to the actual mail server.
Edit the tsm.cf file (in /etc/mail/ or similar) to include
FEATURE(relay_entire_domain)
between the DOMAIN() and MAILER() lines. Since you're editing the file, you may want to also improve security with
define(`confPRIVACY_FLAGS',``noexpn,novrfy'')
After changing the tsm.cf file (or any sendmail config file), restart or SIGHUP the sendmail process.
This change is necessary because the WWW and MX servers for the domain do not exist in the same process space; this FEATURE triggers sendmail to process messages for the domain using it's external delivery mechanism.
The edited portion of the tsm.cf file should look similar to this:
DOMAIN(website.com)dnl
FEATURE(relay_entire_domain)dnl
define(`confPRIVACY_FLAGS',``noexpn,novrfy'')dnl
MAILER(smtp)dnl
MAILER(procmail)dnl
What worked for me was to add an MX record on the webserver hosting the website, that points to the host assigned on the original domain name server. In the case presented here would be an mx record pointing to: mailsec.website.com
I'm new here. Wanted to extend RB_CWI answer, but I am not allowed to comment.
His solution worked great.
You are not required to define the DOMAIN().
However, on my system I was required to install the sendmail-cf package.
The instructions below were done on CentOS 6.5
First, install sendmail-cf
sudo yum install sendmail-cf
Then, edit the senmail.mc
sudo vi /etc/mail/sendmail.mc
At the bottom of the file add FEATURE(relay_entire_domain)dnl, so it looks like:
...
FEATURE(relay_entire_domain)dnl
MAILER(smtp)dnl # right above this line
MAILER(procmail)dnl
dnl MAILER(cyrusv2)dnl
Save the file, and restart sendmail.
sudo service sendmail restart
Got stuck on the same problem. MX points to an external Exchange server but php/sendmail did not lookup this record. Instead mails posted by WordPress on this webserver dropped in the catchall-mailbox.
Solution was to delete ALL mailboxes on the webserver. Now sendmail was interested in the MX and all mails went to the Exchange.
However, the Exchange uses the webspace's mail server as SmartHost for outgoing mails. As solution for this, we were able to use the FTP credentials for accessing the mail server. I assume this solution does not work on every provider on this planet, but in our case (all-inkl.com) it worked out.