550 validating sender failed to meet spf requirements

The ABNF comment for Additional-Registered-Clauses states that "Additional standard clauses may be added in this location by future standards and registration with IANA." 3.

Introduction Definition Challenges Solutions Summary References Welcome to this document from the Midsize Business Security Guidance collection.Microsoft hopes that the following information will help you create a more secure and productive computing environment.No more than 6 groups in addition to the ; "::" may be present.IPv6v4-full = IPv6-hex 5(":" IPv6-hex) ":" IPv4-address-literal IPv6v4-comp = [IPv6-hex *3(":" IPv6-hex)] "::" [IPv6-hex *3(":" IPv6-hex) ":"] IPv4-address-literal ; The "::" represents at least 2 16-bit groups of ; zeros.GMail was rejecting mail sent from my VPS hosted site until I added an AAAA record pointing to one of my allocated IPv6 addresses, since adding this record I've not had any problems.

Is it possible to share an IPv6 record across different domains for an AAAA record in each domain, or is the number of AAAA records that can be created limited to the number of IPv6 addresses allocated by the VPS supplier?That was always the intent of the older two options anyway.This new option is enabled by default and prevents use of reserved IPs from appearing in certain MDaemon created message headers.[13332] The option "POP3, IMAP, and World Client passwords are case sensitive" has been deprecated and removed from Ctrl O | Preferences | Miscellaneous. Allowing otherwise breaks security best practices and is incompatible with hash-based authentication mechanisms (APOP, CRAM-MD5) and secure (hash-based) password storage.As a result of this some of your users may need to update their password in their mail client.This increased flow of junk e-mail continues to challenge midsize businesses.