configure sendmail to use external smtp server

danix85 · 05-07-2018, 11:36 AM

Hello everyone,
I have an OpenVZ VPS on hostus with Slackware64-14.2 on it, I'm trying to configure sendmail to manage only the outgoing queue using an smtp server from namecheap.

I've read a ton of how-tos about this particular purpose, even a few old threads here on lq, but so far I'm stuck.

Here's what I did, on a fresh install of sendmail I've created the directory /etc/mail/auth, inside of it I've put the file client-info with this line in it:

Code:

AuthInfo:your.isp.net "U:root" "I:emailuser" "P:emailpassword"

created the database with:

Code:

makemap hash client-info < client-info

and set the two files like this:

Code:

-rw------- 1 root root  75 May  7 17:52 client-info
-rw------- 1 root root 12K May  7 17:56 client-info.db

I've used the sendmail-slackware.mc to build a cf, I added the lines

Code:

define(`SMART_HOST',`your.isp.net')dnl
define(`confAUTH_MECHANISMS', `EXTERNAL GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN PLAIN')dnl
FEATURE(`authinfo',`hash /etc/mail/auth/client-info')dnl

and then I did:

Code:

m4 sendmail-slackware.mc > slack.cf

backed up the original sendmail.cf shipped with the package and substituted it with my version of it.

started the server and /var/log/maillog says that the server has started, but when I tested it with:

Code:

sendmail -vt < testmail.txt

maillog stated:

Code:

May  7 18:04:54 danix sendmail[23249]: w47G4sjL023249: from=root, size=139, class=0, nrcpts=1, msgid=<201805071604.w47G4sjL023249@mysite.net>, relay=root@localhost
May  7 18:04:54 danix sendmail[23249]: w47G4sjL023249: to=my@email.com, ctladdr=root (0/0), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=30139, relay=[127.0.0.1] [127.0.0.1], dsn=4.0.0, stat=Deferred: Connection refused by [127.0.0.1]

I'm not really sure how to read that log, but I think it shouldn't say that the relay is localhost, but I have no idea of what to modify.

Could you please point me in the right direction?

business_kid · 05-07-2018, 01:14 PM

May I suggest you do nothing and try a test mail to a real email. If that relays through the external server, you're ok.

Sendmail is a server, and your external server is redundancy, although I'm sure you have your reasons for it. It's not surprising that sendmail thinks of itself as the relay. I wouldn't take the log too seriously.

danix85 · 05-07-2018, 02:11 PM

the test mail I tried was towards a real email address but sendmail didn't relay on the external SMTP server. I know sendmail is capable of doing so for outgoing emails but I haven't been able to set it up properly.

the reason for a setup like this is to not to have to setup a fully fledged email server on top of the other services that I want this server to offer, resource and security wise.

having sendmail setup like this means that it is no longer listening for incoming emails, so less room for troubles.

asdrubale · 05-07-2018, 03:21 PM

Quote:

Originally Posted by danix85

Here's what I did, on a fresh install of sendmail I've created the directory /etc/mail/auth, inside of it I've put the file client-info with this line in it:

Code:

AuthInfo:your.isp.net "U:root" "I:emailuser" "P:emailpassword"

I'm using a similar configuration, but in my client-info I have

Code:

"U:smmsp"

instead of

Code:

"U:root"

and it works fine with Gmail SMTP servers.

danix85 · 05-08-2018, 02:27 AM

Quote:

Originally Posted by asdrubale

I'm using a similar configuration, but in my client-info I have

Code:

"U:smmsp"

instead of

Code:

"U:root"

and it works fine with Gmail SMTP servers.

thanks, I tried setting smmsp as the user but the mail keeps getting relied through 127.0.0.1

do you mind posting your config for sendmail? Maybe I'm missing something there.

asdrubale · 05-08-2018, 06:24 AM

Quote:

Originally Posted by danix85

do you mind posting your config for sendmail? Maybe I'm missing something there.

sendmail.cf:

Code:

include(`../m4/cf.m4')
OSTYPE(linux)dnl
define(SMART_HOST, smtp:smtp.gmail.com)dnl
define(`RELAY_MAILER_ARGS', `TCP $h 587')dnl
define(`ESMTP_MAILER_ARGS', `TCP $h 587')dnl
define(`confAUTH_OPTIONS', `A p')dnl
TRUST_AUTH_MECH(`EXTERNAL DIGEST-MD5 CRAM-MD5 LOGIN PLAIN')dnl
define(`confAUTH_MECHANISMS', `EXTERNAL GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN PLAIN')dnl
FEATURE(`authinfo',`hash -o /etc/mail/client-info.db')dnl
FEATURE(always_add_domain)dnl
FEATURE(access_db)dnl
FEATURE(accept_unresolvable_domains)dnl
dnl I don't have visibility to outside my LAN
FEATURE(`accept_unqualified_senders')dnl
dnl to canonify the address you need DNS
FEATURE(`nocanonify')
FEATURE(no_default_msa)dnl
DAEMON_OPTIONS(`Port=smtp, Name=MTA, Addr=127.0.0.1')dnl
DAEMON_OPTIONS(`Port=587, Name=MSA, Addr=127.0.0.1, M=E')dnl
MAILER(local)dnl
MAILER(smtp)dnl

client-info:

Code:

AuthInfo:smtp.gmail.com "U:smmsp" "I:xxxxxxxxx@gmail.com" "P:xxxxxxxxxxxxxxxxxxxxxxxxxxxx"
AuthInfo:smtp.gmail.com:587 "U:smmsp" "I:xxxxxxxxxxx@gmail.com" "P:xxxxxxxxxxxxxxxxxxxxxxxxxxx"

danix85 · 05-09-2018, 12:17 AM

thanks, I'll look into that as soon as I get back home.

I solved with msmtp now but I want to understand what was wrong with my settings.

thanks a lot..