outlook for mac 2016 apply rules to existing messages

OUTLOOK FOR MAC 2016 APPLY RULES TO EXISTING MESSAGES VERIFICATION

The data returned from the query of this record is also a list of tag-value pairs. In that case the label must be encoded according to IDNA before lookup. Note that the selector and the domain name can be UTF-8 in internationalized email. This gives the TXT resource record to be looked up as: The string _domainkey is a fixed part of the specification.

For example, given the example signature above: the d tag gives the author domain to be verified against, the s tag the selector, brisbane.

OUTLOOK FOR MAC 2016 APPLY RULES TO EXISTING MESSAGES VERIFICATION

Verification Ī receiving SMTP server wanting to verify uses the domain name and the selector to perform a DNS lookup. This list need not match the list of headers in h.Īlgorithms, fields, and body length are meant to be chosen so as to assure unambiguous message identification while still allowing signatures to survive the unavoidable changes which are going to occur in transit. In addition to the list of header fields listed in h, a list of header fields (including both field name and value) present at the time of signing may be provided in z. The result, after encryption with the signer's private key and encoding using Base64, is b. For both hashes, text is canonicalized according to the relevant c algorithms. The DKIM-Signature: field of the signature being created, with bh equal to the computed body hash and b equal to the empty string, is implicitly added to the second hash, albeit its name must not appear in h - if it does, it refers to another, preexisting signature. A non-existing field matches the empty string, so that adding a field with that name will break the signature. Repeated field names are matched from the bottom of the header upward, which is the order in which Received: fields are inserted in the header. Second, selected header fields are hashed, in the order given by h. First, the message body is hashed, always from the beginning, possibly truncated at a given length (which may be zero). The semantics of the AUID are intentionally left undefined, and may be used by the signing domain to establish a more fine-grained sphere of responsibility.īoth header and body contribute to the signature. The domain must be equal to, or a subdomain of, the signing domain. The format is an email address with an optional local-part. The most relevant ones are b for the actual digital signature of the contents (headers and body) of the mail message, bh for the body hash (optionally limited to the first l octets of the body), d for the signing domain, and s for the selector.Īn Agent or User Identifier (AUID) can optionally be included.

b (required), signature of headers and body.

z (optional), header fields - copy of selected header fields and values.

h (required), header fields - list of those that have been signed.

i (optional), Agent or User Identifier (AUID).

c (optional), canonicalization algorithm(s) for header and body.

d (required), Signing Domain Identifier (SDID).

The resulting header field consists of a list of tag=value parts as in the example below: The specification allows signers to choose which header fields they sign, but the From: field must always be signed. Signing modules insert one or more DKIM-Signature: header fields, possibly on behalf of the author organization or the originating service provider. The signing organization can be a direct handler of the message, such as the author, the submission site or a further intermediary along the transit path, or an indirect handler such as an independent service that is providing assistance to a direct handler.

Hence, DKIM signatures survive basic relaying across multiple MTAs.

Verifying modules typically act on behalf of the receiver organization, possibly at each hop.Īll of this is independent of Simple Mail Transfer Protocol (SMTP) routing aspects, in that it operates on the RFC 5322 message-the transported mail's header and body-not the SMTP 'envelope' defined in RFC 5321. It does not directly prevent or disclose abusive behavior.ĭKIM also provides a process for verifying a signed message. ĭKIM provides the ability to sign a message, and allows the signer ( author organization) to communicate which email it considers legitimate. System administrators also have to deal with complaints about malicious email that appears to have originated from their systems, but did not.

For example, a fraudster may send a message claiming to be from with the goal of convincing the recipient to accept and to read the email-and it is difficult for recipients to establish whether to trust this message. The need for email validated identification arises because forged addresses and content are otherwise easily created-and widely used in spam, phishing and other email-based fraud.

Outlook for mac 2016 apply rules to existing messages