Linux uses mailx to send SMTP mail and related problems

Linux system uses SMTP to send mail on the server side

preface

Today, I tried the database backup tool provided by LNMP, and found that it is OK. You can back up files and databases locally, and then send them to the remote ftp. Hmm, that's what I want. You can uninstall the plug-in.

Then a friend in the group said that when the backup was successful, he could send an email to notify them, and then think about how this could be achieved. Search for a Mailx software tool on Linux to implement the function of sending mailboxes, and then install it today, which records the process of use, and some pitfalls in the middle.

get ready

First of all, my operating system is centos7, and the mailbox is QQ corporate mailbox.

The first step is to use mailx.
First of all, if the system is normal, it should have its own mailx. If not, it can be easily installed. This is a very small software. Because my operating system is Centos, all commands here use the Red Hat system. Other systems can be replaced by themselves.

 yum -y install mailx

Step 2: Configure Mail
If you need to configure the mailbox on the mail side and the server side and then the fuel tank side, it is unnecessary to say that you must use the smtm. There are many online tutorials set up by yourself. Today's focus is not on the mailbox side, but on sending mail on the server.

First of all, we don't need to think about port 25. It's basically impossible. So we basically use port 465. So when setting, we should first use port 465, and then we should configure it. The parameters are the same as others, and we will set some SMTP values. The path is this file etc/mail.rc

 #The user name authenticated by the smtp server should be consistent with the following user name and account, not in Chinese set from= info@mail.gitcafe.net #Address of smtp server set smtp= smtps://smtp.exmail.qq.com:465 #Email authentication mode set smtp-auth=login #User name authenticated by smtp server set smtp-auth-user= info@mail.gitcafe.net #User password (authorization code) authenticated by smtp server set smtp-auth-password=xxxxxoooooo #Ignore validation set ssl-verify=ignore #The following is the storage location of the certificate set nss-config-dir=/root/.certs/

 echo "mail content" | mail -s "title"  sp91@qq.com

We tried to send an email to ourselves. Then I checked that he could not send it. There was an error. The error here was basically related to the certificate, so we had to save a certificate locally, so we had to redo it.

Because I use QQ mailbox, all commands are related to the limited origin of QQ. If it is other mailboxes, you can change the address of his smtp.

 #The following is the storage location of the certificate mkdir -p /root/.certs/ echo -n | openssl s_client -connect smtp.exmail.qq.com:465 | sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' > ~/.certs/qq.crt certutil -A -n "GeoTrust SSL CA" -t "C,," -d ~/.certs -i ~/.certs/qq.crt certutil -A -n "GeoTrust Global CA" -t "C,," -d ~/.certs -i ~/.certs/qq.crt certutil -L -d /root/.certs cd /root/.certs certutil -A -n "GeoTrust SSL CA - G3" -t "Pu,Pu,Pu"  -d ./ - i qq.crt

After executing this command, try again to test whether you can send mail? It should be possible to send emails this time. Anyway, Yunluo receives emails normally here.

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