Name with a dot causes Spamassassin's FROM_EXCESS_BASE64 to fire

[mariancerny]

Setting $message->from to "hokuspokus.cz <info@hokuspokus.cz>" causes the following header to be generated:

From: =?UTF-8?B?aG9rdXNwb2t1cy5jeg==?= <info@hokuspokus.cz>

This however causes Spamassassin to fire the rule FROM_EXCESS_BASE64=0.979, which means "From: base64 encoded unnecessarily"
https://wiki.apache.org/spamassassin/Rules/FROM_EXCESS_BASE64

[mariancerny]

I can see in MimePart.php, that the encoding is forced when name contains the following characters: .,;<@>()[]"=?

$s .= self::encodeHeader($name, $offset, strpbrk($name, '.,;<@>()[]"=?'));

I understand that it is forced for a reason, but I think that for the case of a plain domain name (single word containing only dots) it should not be escaped.

The definition of the FROM_EXCESS_BASE64 rule in Spamassassin is:

meta FROM_EXCESS_BASE64         __FROM_ENCODED_B64 && !__FROM_NEEDS_MIME
header __FROM_ENCODED_B64       From:raw =~ /=\?\S+\?B\?/i
header __FROM_NEEDS_MIME        From =~ /[\x00-\x08\x0b\x0c\x0e-\x1f\x7f-\xff]/

[dg]

Special chars like dot must be in quoted string, according to RFC 822. Or encoded as base64. This can be somehow changed, but Nette encodes strings when they may exceed 80 chars boundary and Spamassassin seems to not accept even this.

[mariancerny]

Observation: Apple Mail (version 7.3) does not encode sender name in From header when it contains a dot:

From: "example.com" <info@example.com>

[mariancerny]

RFC 822 has been obsoleted by RFC 2822.

If I am reading RFC 2822 correctly, then the name (display-name) does not need to be base64/quoted-printable encoded, just quoted-string (a string in quotes) when it contains the dot (.) character.

Also, those special characters '.,;<@>()[]"=?' in MimePart.php are missing :\ (see specials bellow). In addition =? are there extra. But I understand that is probably there because =? is used for base64/quoted-printable encoding.

So I think that sending mail with name 'example.com'

$mail = new Message;
$mail->setFrom('info@example.com', 'example.com')

should generate header

From: "example.com" <info@example.com>

Relevant parts from RFC 2822:

from            =       "From:" mailbox-list CRLF

mailbox-list    =       (mailbox *("," mailbox)) / obs-mbox-list

mailbox         =       name-addr / addr-spec

name-addr       =       [display-name] angle-addr

display-name    =       phrase

phrase          =       1*word / obs-phrase

word            =       atom / quoted-string

atom            =       [CFWS] 1*atext [CFWS]

atext           =       ALPHA / DIGIT / ; Any character except controls,
                        "!" / "#" /     ;  SP, and specials.
                        "$" / "%" /     ;  Used for atoms
                        "&" / "'" /
                        "*" / "+" /
                        "-" / "/" /
                        "=" / "?" /
                        "^" / "_" /
                        "`" / "{" /
                        "|" / "}" /
                        "~"

quoted-string   =       [CFWS]
                        DQUOTE *([FWS] qcontent) [FWS] DQUOTE
                        [CFWS]

qcontent        =       qtext / quoted-pair

qtext           =       NO-WS-CTL /     ; Non white space controls

                        %d33 /          ; The rest of the US-ASCII
                        %d35-91 /       ;  characters not including "\"
                        %d93-126        ;  or the quote character

specials        =       "(" / ")" /     ; Special characters used in
                        "<" / ">" /     ;  other parts of the syntax
                        "[" / "]" /
                        ":" / ";" /
                        "@" / "\" /
                        "," / "." /
                        DQUOTE