net/mail: ParseAddress does not allow mixed quoted / unquoted local parts

[graywolf]

What version of Go are you using (go version)?

I'm not sure how to get this information from play.golang.org.

Does this issue reproduce with the latest release?

yes

What operating system and processor architecture are you using (go env)?

I'm not sure how to get this information from play.golang.org.

What did you do?

package main

import (
	"fmt"
	"net/mail"
)

func main() {
	input := `foo."x".bar@bar.com`
	fmt.Println(mail.ParseAddress(input))
}

https://play.golang.org/p/OjrtE1S12lP

What did you expect to see?

<foo.x.bar@bar.com> <nil>

What did you see instead?

<nil> mail: no angle-addr

[davecheney]

Section 3.2.3 suggests that the local part of an address may be a dot-atom or a quoted string, but not a combination of both as your example shows. Do mail clients accept this address?

[graywolf]

There is also section 4.4 describing obs-local-part = word *("." word) so that email address should be valid. Also mail send like

$ sendmail -t
From: me@some.domain
To: foo."x".bar@some.domain
Subject: Test

Test.

does arrive.

Note: While section 4 is obsolete, it must be accepted.

Though these syntactic forms MUST NOT be generated according to the grammar
in section 3, they MUST be accepted and parsed by a conformant receiver.

[davecheney]

I read “.” as one literal period character

[graywolf]

Well yeah, so the obs-local-part in foo."x".bar should be evaluated like atom "." quoted-string "." atom, which looks valid based on:

obs-local-part  =   word *("." word)
word            =   atom / quoted-string

Am I reading the RFC wrong?

[davecheney]

Tbh I’m not sure. What’s your use case? Do you have a need to accept this form of address?

[graywolf]

I've tried to put list of valid email addresses [0] through our email validation and some did not pass. So it seemed reasonable to open a bug report about this. If full RFC 5322 compatibility is not a desired goal, then this can be closed.

[0] https://github.com/StoneCypher/testdata-valid-email/blob/master/testdata-valid-email.js