Since "US MAILACCESS.txt" is not a recognized formal standard, it likely refers to a local technical configuration file or a draft document for an internal or Simple Mail Transfer Protocol (SMTP) implementation.
Known malicious sources to be summarily declined. US MAILACCESS.txt
This draft assumes familiarity with ARPA standard mail formats (RFC 5321/5322). It is intended to be used in conjunction with localized firewall rules to restrict access to proprietary mail servers, especially for systems that require specific restricted IP source addresses or browser-based logins. Since "US MAILACCESS