Email reaction examples

Here are several samples of valid and invalid email reaction messages.

Valid multipart/alternative

Email reactions usually have three parts:

• text/plain: the plain text version of the message.
• text/vnd.google.email-reaction+json: the reaction part.
• text/html: the HTML version of the message.

Here's an example:

From: [e-mail]
Message-ID: <[e-mail]>
Subject: subject
MIME-Version: 1.0
In-Reply-To: <[e-mail]>
Content-Type: multipart/alternative;
        boundary="----=_Part_0_2012232625.1697791227635"

------=_Part_0_2012232625.1697791227635
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit

Text body content
------=_Part_0_2012232625.1697791227635
Content-Type: text/vnd.google.email-reaction+json; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

{"emoji":"=F0=9F=99=83","version":1}
------=_Part_0_2012232625.1697791227635
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

<h1>HTML body content</h1>
------=_Part_0_2012232625.1697791227635--

Single valid body part

Email reactions can also just have a single body part like:

From: [e-mail]
Message-ID: <[e-mail]>
Subject: subject
MIME-Version: 1.0
In-Reply-To: <[e-mail]>
Content-Type: text/vnd.google.email-reaction+json; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

{"emoji":"=F0=9F=99=83","version":1}

Note that the Content-Transfer-Encoding can be any standard encoding:

From: [e-mail]
Message-ID: <[e-mail]>
Subject: subject
MIME-Version: 1.0
In-Reply-To: <[e-mail]>
Content-Type: text/vnd.google.email-reaction+json
Content-Transfer-Encoding: base64

ewogICJlbW9qaSI6ICLwn46JIiwKICAidmVyc2lvbiI6IDEKfQ==

For binary encodings, like base64, the JSON must be encoded as UTF-8.

Valid nested multipart/alternative in multipart/related

If the reaction is to a message that had inline attachments, it's possible to generate a message with a multipart/related body part that contains the attachments plus a multipart/alternative part like the previous example.

From: [e-mail]
Message-ID: <[e-mail]>
Subject: subject
MIME-Version: 1.0
In-Reply-To: <[e-mail]>
Content-Type: multipart/related;
        boundary="----=_Part_0_2012232625.1697793303618"

------=_Part_0_2012232625.1697793303618
Content-Type: multipart/alternative;
        boundary="----=_Part_1_984213526.1697793303621"

------=_Part_1_984213526.1697793303621
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit

Text body content
------=_Part_1_984213526.1697793303621
Content-Type: text/vnd.google.email-reaction+json
Content-Transfer-Encoding: base64

ewogICJlbW9qaSI6ICLwn46JIiwKICAidmVyc2lvbiI6IDEKfQ==
------=_Part_1_984213526.1697793303621
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

<h1>HTML body content</h1>
------=_Part_1_984213526.1697793303621--

------=_Part_0_2012232625.1697793303618
Content-Type: text/vnd.google.email-reaction+json
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="1x1.png"

iVBORw0KGgoAAAANSUhEUgAAAAEAAAABAQMAAAAl21bKAAAAA1BMVEUAAACnej3aAAAAAXRSTlMA
QObYZgAAAApJREFUCNdjYAAAAAIAAeIhvDMAAAAASUVORK5CYII=
------=_Part_0_2012232625.1697793303618--

(Note that the multipart/related body part should have other fields as specified by RFC2387 but those are irrelevant for determining whether an email reaction is valid.)

Invalid JSON format

The following reaction is invalid because the JSON is missing the closing brace:

From: [e-mail]
Message-ID: <[e-mail]>
Subject: subject
MIME-Version: 1.0
In-Reply-To: <[e-mail]>
Content-Type: text/vnd.google.email-reaction+json; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

{"emoji":"=F0=9F=99=83","version":1

The following reaction is invalid because the JSON has a trailing comma:

From: [e-mail]
Message-ID: <[e-mail]>
Subject: subject
MIME-Version: 1.0
In-Reply-To: <[e-mail]>
Content-Type: text/vnd.google.email-reaction+json; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

{"emoji":"=F0=9F=99=83","version":1,}

Invalid version field

The following reaction is invalid because it's missing the version field:

From: [e-mail]
Message-ID: <[e-mail]>
Subject: subject
MIME-Version: 1.0
In-Reply-To: <[e-mail]>
Content-Type: text/vnd.google.email-reaction+json; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

{"emoji":"=F0=9F=99=83"}

The following reaction is invalid because the version field isn't 1:

From: [e-mail]
Message-ID: <[e-mail]>
Subject: subject
MIME-Version: 1.0
In-Reply-To: <[e-mail]>
Content-Type: text/vnd.google.email-reaction+json; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

{"emoji":"=F0=9F=99=83","version":2}

Invalid emoji field

The following reaction is invalid because the emoji field is empty:

From: [e-mail]
Message-ID: <[e-mail]>
Subject: subject
MIME-Version: 1.0
In-Reply-To: <[e-mail]>
Content-Type: text/vnd.google.email-reaction+json; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

{"emoji":"","version":1}

The following reaction is invalid because the emoji field doesn't contain a valid emoji.

From: [e-mail]
Message-ID: <[e-mail]>
Subject: subject
MIME-Version: 1.0
In-Reply-To: <[e-mail]>
Content-Type: text/vnd.google.email-reaction+json; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

{"emoji":"A","version":1}

The following reaction is invalid because the ❤ emoji is missing between the two zero-width joiner (ZWJ) characters. Note that the = character at the end of the first content line represents a soft line break in the Quoted-Printable encoding.

From: [e-mail]
Message-ID: <[e-mail]>
Subject: subject
MIME-Version: 1.0
In-Reply-To: <[e-mail]>
Content-Type: text/vnd.google.email-reaction+json; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

{"emoji":"=F0=9F=91=A9=F0=9F=8F=BC=E2=80=8D=E2=80=8D=F0=9F=91=A8=F0=9F=8F=BE",=
"version":1}