Collection of email defects spotted in the wild.

email_defects.md

Formats

EML/IMF

General advice: ...

Title	Description	Reference	Observed in	Reported	Status	Comment

Protocols

IMAP

Note: "[...] do not attempt to deduce command syntax from the command section alone; instead refer to the Formal Syntax section."

Defects

Title	Description	Reference	Observed in	Reported	Status	Comment
Zero UID	UID MUST be >= 1 but was 0	uniqueid = nz-number RFC 3501	Outlook	No	Unknown
Negative line length	body-fld-lines should be >= 0 and < 4_294_967_296 but was -1	body-fld-lines = number RFC 3501	Dovecot	No	Unknown
Missing text	HIGHESTMODSEQ status should have a text but didn't	https://www.rfc-editor.org/rfc/rfc7162 section 7	Gmail	Yes	Open	Examples in RFC are wrong. Errata?

Ambiguities

• code and text didn't play well ...

Greeting { kind: Ok, code: None, text: "[FOO] ..." }

... will result in ...

* OK [FOO] ...

... and be interpreted like ...

Greeting { kind: Ok, code: Foo, text: "..." }

And ...

Greeting { kind: Ok, code: None, text: "[...]" }

... can't be expressed.

• Unclear command continuation response(s).
  • When is base64 allowed in command continuation response?

`+ Rm9vbw==` could be interpreted as "Fooo" (base64) or just "Rm9vbw==" (text).

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