LuxSci SMTP TLS Checker is a free online tool that analyzes the TLS configuration of inbound email servers for any given domain. It evaluates the quality of SMTP TLS support, helping administrators understand how well a domain's mail infrastructure handles encrypted connections. The tool is part of LuxSci's broader SecureLine™ email encryption offering, which supports TLS-based secure email delivery. Key capabilities associated with the platform include: - Dynamically detecting whether recipient domains support TLS, without requiring manual pre-configuration. - Automatic fallback to alternative email encryption modes when TLS is unavailable. - Optional configuration to allow or block TLS-only email delivery per domain or recipient. - Option to prevent email delivery to recipients who do not support TLS, relevant in compliance contexts such as HIPAA. - API access for programmatically checking domain TLS support prior to sending email. - API access for sending secure email messages without using SMTP directly. Results can optionally be kept private and re-tests can be run to bypass cached results. The checker is intended for email administrators, security professionals, and organizations that need to verify and enforce TLS encryption standards for email delivery.