How to setup Sendmail as SMTP Relay?

adshocker · 05-15-2011, 06:43 PM

Hi Guys,

I want to setup sendmail using my username and password on my ISP to be able to send out messages.

I'm using Linux. So far, what I've done is modified the sendmail.mc with the following changes:

Code:

define(`SMART_HOST',`mysmtpoutgoingserver')
FEATURE(authinfo)dnl

In my /etc/mail/authinfo, I have the following:

Code:

AuthInfo:mysmtpoutgoingserver "U:myusername@myispdomain" "I:myusername@myispdomain" "P:mypassword" "M:PLAIN"

Now whenever I try sending by executing a simple sendmail command:

Code:

cat sendmail.mc | sendmail "myotheremail@gmail.com"

I always get a Sender Rejected error mail back.

Code:

(reason: 550 5.1.8 <root@mylocaldomain>: Sender address rejected: Domain not found)

This is actually true as the mylocaldomain is not a public Internet domain. Just a localdomain for our local network. However, I was expecting that to change to the username in my authinfo "myusername@myispdomain" since this account is authorized to send out email with my ISP.

Any ideas on how I can do this?

Thanks.

T3RM1NVT0R · 05-15-2011, 08:41 PM

Hi there,

Well, I don't think so it is possible to do what you are trying.

Here you are trying to use one email account that you have with your ISP to be used to send email address by relaying.

You are using internal email account that you have created on your sendmail server and trying to link it with your email account that you have with your ISP which I think is a sort of relaying and which wouldn't be permitted either by your ISP or by any email server on the internet due to the fact that it can be used to flood the mailserver with such messages.

The only option is to get your domain name registered, get a public IP, configure mx record for your mailserver and do NATing for security.