2822upd-04 section 3.6.8 reads in part:
field-name = 1*ftext
That specifies unlimited length, which conflicts with line length limits
specified in section 2.1.1.
field-name = 1*77ftext
would conform to the lower recommended limit. [for reference, the
longest field name that I know of defined in a published RFC is
Delivery-Report-Content-Reported-Recipient-Info (47 characters)
defined in RFC 987.]
2822upd-04 section 4.5.8 reads:
4.5.8. Obsolete optional fields
obs-optional = field-name *WSP ":" unstructured CRLF
[off-topic] unlike most sections, this one lacks vertical whitespace between
section heading and text.
This one probably needs an obs-field-name as RFC 733 permitted space/tab
within (but not at the start of, for obvious reasons) a field-name (and it
is occasionally necessary to parse old messages).