If you are hosting your PHP using CentOS in Azure, the chances are high that you will hit this issue. Basically, if your PHP code uses mail() function to send mail for notifications, you might find that it is not sending the mails as you anticipated it to. It is because, PHP mail uses
sendmail to send its mail. So ensure that you have
sudo yum install sendmail
Also install the mail client so that you can be sure that the mail is flying well.
sudo yum install mailx
When you issue the following command, you will get in a writing mode. You can write a small test letter. When you are done, type . (period) and hit enter. It should say EOT and your mail should reach you.
mail -s "Test Mail" firstname.lastname@example.org
If you don’t receive the mail, it means there is something wrong. In the folder mentioned below you can find your mails undelivered.
sudo ls -la /var/spool/clientmqueue
You can do a
cat on them and find the error message. In my CentOS 7 install image (on Azure), I found the following error:
MDeferred: Connection refused by [127.0.0.1]
Clearly, there is something missing! The mail is not getting sent, because it is actively getting refused by the local server. Open the file, and modify it so that it has 127.0.0.1 in one of the lines.
sudo vi /etc/mail/local-host-names
Something like this should do…
# local-host-names - include all aliases for your machine here. 127.0.0.1 localhost
Restart your service.
sudo service sendmail restart
Check your mail, and you should be able to find your stuck mails being delivered (most likely in your spam folder ;-).
Hope this helps!