In order to set up a post via email functionality for your WordPress installation, you need to first set up an email account for it. On SiteGround servers you can do so via cPanel -> Email Accounts.

The next step is to add this account in your WordPress installation. To do so, log in to the administrative backend for WordPress, go to Settings -> Writing and under the Post via Email section enter the needed details:

Mail Server: <your domain name>
Port: 110
Login Name: <the full email address>
Password: <the corresponding password for the mail account above>

For example:

Mail Server: mywebsite.com
Port: 110
Login Name: secret_wordpress_email@mywebsite.com
Password: MySTRongP@ss

Generally, those are all the settings you need to adjust in order for the Post via email functionality to work.

What you need to do after that is visit the corresponding URL for your WordPress installation so the email messages are parsed. The URL is of type:

http://yourdomain.com/wordpress/wp-mail.php

Where:

yourdomain.com - is your actual domain name
wordpress - is the path to your WordPress installation. This might be skipped if WordPress is installed directly under the webroot for your domain.

Or if we presume you are using the domain name mentioned in the previous example and the WordPress installation is under directory blog:

http://mywebsite.com/blog/wp-mail.php

Note that by default such posts are not automatically displayed on your WordPress front page. They still need to be published via the WordPress administrator area. Alternatively, you can adjust your WordPress configuration to automatically submit posts without being approved by an administrator. This is up to your specific preferences.