WHMCS offers advanced settings for the configuration of the mail provider. You have the possibility to choose from a list of providers: PHP Mail (default one), SMTP, Mailgun, SendGrid and SparkPost.

To configure the WHMCS Mail Provider follow the steps:

1. Log in to the WHMCS admin area

2. Go to System Settings >> General Settings

3. Choose the Mail tab and click the Configure Mail Provider button. A popup box will open.

4. Choose the Mail Provider, enter the details for it and click the Save button.


Mail provider 1: PHP Mail

This option will use the PHP mail() function. The only option available here is Mail Encoding.

Mail provider 2: SMTP

This will probably be the most used mail provider by users. There are many SMTP options that can be configured here:

Mail Encoding the email encoding that will be used – 7bit, 8bit, binary, base64, quoted-printable
Service Provider generic or Google.
SMTP Host the SMTP mail server. Usually, this is mail.yourdomain.com
SMTP Port the SMTP port. By default, this is 465 or 587. On most servers, both ports will be open.
SMTP Authentication password or Oauth2. OAuth is an open standard for access to applications/websites.
SMTP Username the SMTP account username. In most cases, it will be the email address.
SMTP Password the SMTP account password (if you chose the ‘password’ SMTP authentication method)
SMTP SSL Type SSL or TLS. Transport Layer Security (TLS) is the successor of SSL (Secure Sockets Layer)
SMTP Debug this will enable debug logging for SMTP operations
SMTP Options

Mail provider 3: Mailgun

Mailgun – mailgun.com – is an email service delivery. Options here are:

Mailgun Region You can select the EU or US region
Sending Domain domain sending the emails
Mailgun Private API Key your API key – can be found in your Mailgun account

Mail provider 4: SendGrid

SendGrid – sendgrid.com – is another email delivery service. With the Free account, you can send 100email/day. The only option that WHMCS needs is the SendGrid API Key.

Mail provider 4: SparkPost

SparkPost – sparkpost.com – is another email sending platform. The free/test SparkPost account also has 100emails/day. The WHMCS options are:

SparkPost Account SparkPost (by default) or SparkPost EU
SparkPost API Key your SparkPost API key
Use Sink Testing read more about this option here https://support.sparkpost.com/docs/faq/using-sink-server
whmcs mail provider
WHMCS Configure Mail Provider

Related articles:
How to configure Mail Settings in WHMCS