ALLOWNEWSOURCES

ALLOWNEWSOURCES is a configuration directive found in certain software, most notably in some email client or server software, that controls whether new or unknown sender email addresses are permitted to send messages to a particular recipient or system. When ALLOWNEWSOURCES is enabled, the system will accept emails from addresses it has not previously interacted with. Conversely, if it is disabled, the system may reject or flag emails from new senders, potentially as a security measure to combat spam or phishing attempts.

The primary purpose of this setting is often related to security and spam filtering. By default, many systems are configured to allow new sources to send emails, as blocking them would prevent legitimate communication from new contacts. However, in environments where security is paramount or where spam is a significant issue, administrators may choose to disable ALLOWNEWSOURCES. This can be part of a broader strategy to enforce stricter sender verification protocols, such as requiring senders to be whitelisted or to pass specific authentication checks before their emails are delivered.

The implementation and effect of ALLOWNEWSOURCES can vary depending on the specific software. Some systems might offer granular control, allowing new sources for certain domains but not others. Others may have a binary on/off switch. Understanding this setting is crucial for system administrators and users who are managing email security and deliverability to ensure that important messages are not inadvertently blocked while minimizing the risk of unwanted or malicious content.