Mail Providers determine how your installation sends mail. The mail provider you choose can affect your mail deliverability. You can configure mail providers at Configuration () > System Settings > General Settings > Mail, or, prior to WHMCS 8.0, Setup > General Settings > Mail.
Prior to WHMCS 8.0, WHMCS supported two mail providers: PHP Mail and SMTP. In WHMCS 8.0 and later, WHMCS supports three additional mail providers: MailGun, SendGrid, and SparkPost. Additionally, SMTP supports OAuth authentication via Google.
For more information about configuring your mail provider, see Configuring Mail Providers.
MailGun, SendGrid, and SparkPost
To set this up, you will need some information from your email service provider, including an API key.
SMTP uses an SMTP server to send email. You will need to retrieve the SMTP configuration information from your control panel or hosting provider or from Google. The requirements depend on the authentication type you choose.
SMTP with OAuth
WHMCS includes OAuth support for Google email in version 8.0 and later. OAuth is a technology that authorizes apps or services like WHMCS to access another service, such as a Google email account. It's more secure than traditional username-and-password authentication.
Some mail providers require OAuth or have announced a requirement for it in the future.
For instructions to set up OAuth for Google email and the required Google app, see Setting Up Google As Your Mail Service Provider.
When you choose PHP Mail, you won't need to configure any additional settings.
PHP Mail is more likely to be considered spam by spam filtering applications.
You can extend the selection of mail providers with custom modules. For more information, consult our Mail Providers developer documentation.