hi，
Both SMTP and mail() will fail。
Use the Gmail service

Hi,

Open sys/CODOF/Forum/Notification/Mail.php

On line 60, replace

$mail->SMTPDebug = 0;  // debugging: 1 = errors and messages, 2 = messages only

with

$mail->SMTPDebug = 1;  // debugging: 1 = errors and messages, 2 = messages only

Now, try sending a test mail with the same details, you should see more debug information to help with why its failing.

2019-10-15 09:35:06 SMTP ERROR: Failed to connect to server: (0) SMTP connect() failed.

After installing the following tutorial, mail() shows success, but the test message is not actually received.

1、Reinstall the sendmail component, I am using CentOS, use the following command to install

apt-get install sendmail

2、Restart the php-fpm process with the following command

/etc/init.d/php-fpm restart

3、Check if sendmail is working properly.

/etc/init.d/sendmail status

If the display is running running, you can.

Possible commands

/etc/init.d/sendmail start (starts sendmail)

/etc/init.d/sendmail stop (closes sendmail)

/etc/init.d/sendmail restart (restart sendmail)

4、Configure php.ini and fill in the absolute path of sendmail

Use the command to open the edit php.ini

Vi /usr/local/php/etc/php.ini

Enter ?sendmail_path to find the location (or manually jump to find sendmail_path), you will find the default is the following code

;sendmail_path =
Press i to enter the edit and change this line to

Sendmail_path = /usr/sbin/sendmail -t –i

Press Esc to exit editing, type :wq to save and exit

5、Restart the php-fpm process

/etc/init.d/php-fpm restart

It may be that the ports are blocked by your hosting provider. Can you check that ?