3.8 Input Requirements

3.8. Input Requirements

A message that is not compliant with [RFC5322], [RFC2045], and [RFC2047] can be subject to attempts by intermediaries to correct or interpret such content. See Section 8 of [RFC4409] for examples of changes that are commonly made. Such "corrections" may invalidate DKIM signatures or have other undesirable effects, including some that involve changes to the way a message is presented to an end user.

Accordingly, DKIM's design is predicated on valid input. Therefore, Signers and Verifiers SHOULD take reasonable steps to ensure that the messages they are processing are valid according to [RFC5322], [RFC2045], and any other relevant message format standards.

See Section 8.15 for additional discussion.