How an Operating system send notifications to external email

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mashkoorqadir
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How an Operating system send notifications to external email

Post by mashkoorqadir » 2018/06/19 11:40:00

Good Evening to every one.

Can one help me to find the answer.

How a fresh installed system can send notifications to an external email server (e.g abc@gmail.com or abc2@yahoo.com)? The server is only connected to the internet. I didn't configure any smtp server. just have an entry about notification in the crontab.
Which SMTP server does CentOS uses by defualt?

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avij
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Re: How an Operating system send notifications to external email

Post by avij » 2018/06/19 11:57:19

Emails do not need to be sent through your ISP's mail server (unless your ISP prohibits that by blocking outgoing SMTP connections). Your server can send the emails to the destination mail server directly without any other mail server in between. This configuration does not need a "default" mail server at all.

mashkoorqadir
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Re: How an Operating system send notifications to external email

Post by mashkoorqadir » 2018/06/19 12:16:51

Thanks Avij,

But how it is possible without configuring the SMTP it sends notifications? I need to understand this behavior.

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avij
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Re: How an Operating system send notifications to external email

Post by avij » 2018/06/19 12:25:58

Perhaps you have something like postfix installed. It is installed by default in various cases. Postfix does not need any particular configuration to send emails, and some things like your domain name are determined automatically.

For example, if your server needs to send an email to some yahoo.com email address, postfix will query the DNS for yahoo.com's MX (mail exchange) record (see for example dig mx yahoo.com if you have the bind-utils package installed). That way postfix gets to know that any emails destined to yahoo.com should be sent to mta5.am0.yahoodns.net (or one of the alternatives). Postfix can then send the email by itself.

mashkoorqadir
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Joined: 2012/06/27 07:55:01

Re: How an Operating system send notifications to external email

Post by mashkoorqadir » 2018/06/20 10:43:18

ok,

Thanks Avij, for clearing my concept.

Have good day dear.

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