About roaming authentication email services
A roaming authentication service enables your site users to access their domain’s mail server from anywhere outside the network.
You need to have a roaming authentication service if:
You have roaming customers and want your mail server to be accessible to them while on the move
You want to restrict access to authentic users so that your mail server is not vulnerable to spamming from unauthenticated sources
You can opt for any of the following roaming authentication services:
Poprelay
SMTP-AUTH
If you are using Poprelay, users only need to check their mails once in order to use their domain mail server to relay messages. If you are using SMTP_AUTH, you need to configure your email client to send your user name and password for authentication each time you want to connect to your domain mail server. SMTP_AUTH is a more secure authentication service than Poprelay.
Note: You can select the appropriate authentication service when you configure your mail client. By default, Poprelay is enabled by the control panel. To use SMTP_AUTH, you must select the SMTP_AUTH tag (this will depend on the mail client you are using) and provide the authentication user name and password.
For information on how to configure your mail client, see the program's documentation.