Third-Party Email Service

Third-Party Email Service lets you maintain multiple SMTP sending accounts for the same application and select a sender by recipient email allowlist or traffic weight. It supports registration activation codes, sign-in verification codes, password-reset verification codes, and multi-factor authentication emails.

Path: Sign in to the RootAuth Console → select the target application → click Configuration in the top navigation → Branding → Email → Third-Party Email Service.

 

1. Overview

• Each application can save up to five SMTP configurations.
• You can set traffic weights for different SMTP configurations. When a recipient does not match an email allowlist, the system randomly selects a sending account according to relative weights.
• You can add an email allowlist to an SMTP configuration. When a recipient matches the allowlist, the system prioritizes that SMTP configuration and does not use traffic weight selection.
• The display order of SMTP configurations does not represent the actual sending order.

 

2. Enable and Manage SMTP Configurations

2.1 Enable Third-Party Email Service

The Enable Third-Party Email Service switch is off by default. You can save SMTP configurations first, but saving a configuration only stores the settings and does not automatically enable third-party email sending.

• When the switch is enabled: The system sends email to application users according to the SMTP sending rules on this page.
• When the switch is disabled: All email continues to use the default RootAuth domain. Saved SMTP configurations are retained and can be managed the next time the service is enabled.
• Disabling the service removes the current unsaved new configuration. Save or cancel the current edit first.

 

2.2 Create an SMTP Configuration

Click New, then complete the form at the bottom of the SMTP configuration list. The number of saved configurations appears as SMTP Configurations n/5. You cannot create more configurations after reaching five.

Field	Description	Required
SMTP address	The SMTP server address, for example smtp.example.com.	Yes
Port	The SMTP server port. The default is 465.	Yes
Username	The username used to sign in to the SMTP server.	Yes
Password	The SMTP authentication password.	Yes
Sender email	The sender email address shown when an email is sent.	Yes
Custom name	The display name of the sender, for example RootAuth.	No
Traffic weight	The relative traffic split for email that does not match an allowlist.	Yes
Email allowlist	Recipient email addresses or email domains that should use this SMTP configuration first.	No
Security verification	Choose SSL or TLS. SSL is the default.	Yes

2.3 Test and Save

1. After you enter the SMTP connection details, click Test Configuration and Send Email.
2. After the test succeeds, click Save to save the current SMTP configuration.
3. If you only change the Traffic Weight or Email Allowlist of a saved configuration, you can save directly without retesting. If you change the server, port, username, password, or other connection details, you must test successfully before saving.

Unsaved or incomplete SMTP configurations do not participate in actual email sending.

 

2.4 View, Edit, and Delete

• Saved configurations appear in reverse creation order, with the newest first. Expand a card to view its details. The display order does not represent sending priority.
• Click Edit to modify the current SMTP configuration. You can create or edit only one configuration at a time. Save or cancel the current edit before working on another configuration.
• When Third-Party Email Service is enabled and there is only one available SMTP configuration, it cannot be deleted. You can delete an unused SMTP configuration when the service is disabled or when multiple configurations are available. Type DELETE to confirm deletion.

 

3. Traffic Weights

Traffic weights determine how email that does not match an email allowlist is distributed across multiple SMTP accounts.

• Traffic weight is required and must be a number greater than or equal to 0. There is no maximum value.
• SMTP weights do not need to add up to 100. The system makes random selections according to the relative values of the accounts.
• An SMTP configuration with a weight of 0 does not participate in standard traffic splitting, but it can still send email for recipients that match its email allowlist.

For example, if two accounts have weights of 1 and 3, email that does not match an allowlist is more likely to be sent by the account with a weight of 3. Over time, actual sending results increasingly approach the configured ratio.

 

4. Email Allowlists

Use an email allowlist to specify a preferred sending account for particular recipients. Allowlists are optional. You can add entries individually or in batches, with up to 100 entries for each SMTP configuration.

Input format	Matching rule
user@example.com	Exact email matching. The recipient matches only when its email address is exactly the same.
@example.com	Email domain matching. The recipient matches when its email domain is example.com.

For batch addition, separate multiple complete email addresses or email domains beginning with @ using English commas. After parsing, the system adds each item as an individual entry. Correct any invalid entries before saving.

Email allowlists take priority over traffic weights. Even if the current SMTP configuration has a traffic weight of 0, recipients that match its allowlist use this SMTP configuration to send email.

 

5. Email Sending Rules

1. The system first checks whether a recipient matches the email allowlist of a saved, complete SMTP configuration.
2. If the same recipient matches the allowlists of multiple SMTP configurations, the system uses the SMTP configuration created earliest.
3. If no allowlist matches, the system randomly selects an SMTP account from saved, complete configurations with traffic weights greater than 0, based on their relative weights.
4. If a randomly selected or allowlist-matched SMTP configuration fails to send an email, the system does not automatically switch to another SMTP configuration. The email fails for that attempt.

6. Relationship with Email Templates

Email template content is configured independently. When Third-Party Email Service is enabled, the actual sender email address is determined by the email allowlist and traffic weight rules on this page. When the service is disabled, the system uses the default RootAuth domain for all email.

 

7. Configuration Recommendations

• Before enabling Third-Party Email Service, test each SMTP configuration and confirm that test email is delivered successfully.
• Create email allowlists for partners, internal domains, or important recipients that need a fixed sender.
• Set a traffic weight greater than 0 for SMTP configurations that should participate in standard sending, and regularly check their availability and sending limits.