Send messages with MIME content

Many email clients can send messages through Exchange in a MIME message format and communicate across multiple email platforms.

The Outlook mail API supports the following actions on messages with MIME content:

  • Send messages.
  • Send reply or reply-all messages.
  • Forward messages.
  • Create draft messages.
  • Attach S/MIME signatures to a messages.
  • Encrypt message content using S/MIME.

Important

  • S/MIME provides two key features: digital signatures to verify sender and email contents, and message encryption to prevent third parties from viewing email contents.
  • Add S/MIME digital signatures and encrypted content to emails only in their MIME message format.

For more information on MIME format, see getting MIME content of a message.

Use cases

Use cases API method
Create a message draft createMessage
Send an email sendMail
Reply to a message reply
Create a draft to reply to a message createReply
ReplyAll to a message replyAll
Create a draft to replyAll to a message createReplyAll
Forward a message forward
Create a draft to forward a message createForward

Specify request header and MIME message body

You can create a message in JSON or MIME format. Specify the intended format in the request header:

  • Content-Type: application/json to use JSON format in the request body.
  • Content-Type: text/plain to use MIME format in the request body.

When specifying the body in MIME format, provide the applicable Internet message headers and the MIME content, and encode them in base64 format in the request body. Microsoft Graph does not support editing or updating MIME properties individually.

Example

The following is an example of MIME content with Internet message headers (before encoding):

Received: from contoso.com (10.194.241.197) by 
contoso.com (10.194.241.197) with with HTTPS; Thu, 6 May 2021
 22:47:18 +0000
Received: from contoso.com (10.194.241.197)
 by contoso.com (10.194.241.197) with
 SMTP Server (version=TLS1_2, 
cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384_P256) id 15.1.1374.0 via Mailbox; Thu, 6 May
 2021 22:47:15 +0000
Received: from contoso.com 
(fe80::5bf:5059:4ca0:5017) by contoso.com 
(fe80::5bf:5059:4ca0:5017%12) with mapi id 15.01.1374.000; Thu, 6 May 2021
 22:47:14 +0000
From: Adele Vance <AdeleV@contoso.com>
To: Alex Wilber <AlexW@contoso.com>
CC: Christie Cline <ChristieC@contoso.com>
Subject: Testing the MIME feature in Graph
Thread-Topic: Testing the MIME feature in Graph
Thread-Index: AQHTJWSHSywMzSz8o0OJud48nG50GQ==
Date: Thu, 6 May 2021 22:47:14 +0000
Message-ID:
	<4aade2547798441eab5188a7a2436bc1@contoso.com>
Accept-Language: en-US
Content-Language: en-US
X-MS-Exchange-Organization-AuthAs: Internal
X-MS-Exchange-Organization-AuthMechanism: 04
X-MS-Exchange-Organization-AuthSource: contoso.com
X-MS-Has-Attach: yes
X-MS-Exchange-Organization-Network-Message-Id:
	0ffdb402-ec03-42c8-5d32-08d4f37bb517
X-MS-Exchange-Organization-SCL: -1
X-MS-TNEF-Correlator:
X-MS-Exchange-Organization-RecordReviewCfmType: 0
x-ms-publictraffictype: Email
x-originating-ip: [123.456.789.012]
x-ms-traffictypediagnostic: ASDFG12HJ3456:
X-Microsoft-Antispam-Mailbox-Delivery:
	ucf:0;jmr:0;auth:0;dest:I;ENG:(750129)(520011016)(706158)(944506458)(944626604);
X-Microsoft-Antispam-Message-Info:
	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
Content-Type: multipart/mixed;
	boundary="_004_MN2PR13MB3152FA5D970E0F158DF41456D5579MN2PR13MB3152namp_"
MIME-Version: 1.0

--_000_MN2PR13MB3152B5FCA9912BEA2E490189D5589MN2PR13MB3152namp_
Content-Type: text/plain; charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable

Hello Alex,

We are testing the Graph MIME feature.

Kind regards,

Adele

--_000_MN2PR13MB3152B5FCA9912BEA2E490189D5589MN2PR13MB3152namp_
Content-Type: text/html; charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable

<html>
<head>
<meta http-equiv=3D"Content-Type" content=3D"text/html; charset=3Diso-8859-=
1">
<style type=3D"text/css" style=3D"display:none;"> P {margin-top:0;margin-bo=
ttom:0;} </style>
</head>
<body dir=3D"ltr">
<div style=3D"font-family: Calibri, Arial, Helvetica, sans-serif; font-size=
: 12pt; color: rgb(0, 0, 0);">
Hello Alex,&nbsp;</div>
<div style=3D"font-family: Calibri, Arial, Helvetica, sans-serif; font-size=
: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style=3D"font-family: Calibri, Arial, Helvetica, sans-serif; font-size=
: 12pt; color: rgb(0, 0, 0);">
We are testing the Graph MIME feature.&nbsp;</div>
<div style=3D"font-family: Calibri, Arial, Helvetica, sans-serif; font-size=
: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style=3D"font-family: Calibri, Arial, Helvetica, sans-serif; font-size=
: 12pt; color: rgb(0, 0, 0);">
Kind regards,</div>
<div style=3D"font-family: Calibri, Arial, Helvetica, sans-serif; font-size=
: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style=3D"font-family: Calibri, Arial, Helvetica, sans-serif; font-size=
: 12pt; color: rgb(0, 0, 0);">
Adele</div>
</body>
</html>

--_000_MN2PR13MB3152B5FCA9912BEA2E490189D5589MN2PR13MB3152namp_--

The following is the corresponding base64-encoded string:

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

To include a file attachment, append the file metadata and Content-Transfer-Encoding header in base64 to the MIME content:


--_004_MN2PR13MB3152FA5D970E0F158DF41456D5579MN2PR13MB3152namp_
Content-Type: application/vnd.openxmlformats-officedocument.wordprocessingml.document;
	name="Proposed_agenda_topics.docx"
Content-Description: Proposed_agenda_topics.docx
Content-Disposition: attachment; filename="Proposed_agenda_topics.docx";
	size=707560; creation-date="Fri, 07 May 2021 14:06:45 GMT";
	modification-date="Fri, 07 May 2021 14:07:28 GMT"
Content-Transfer-Encoding: base64

UEsDBBQABgAIAAAAIQA9xUZS1AEAALMLAAATAAgCW0NvbnRlbnRfVHlwZXNdLnhtbCCiBAIooAAC
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
ZW0yLnhtbC5yZWxzUEsBAi0AFAAGAAgAAAAhAHvzAqPDAAAAKAEAAB4AAAAAAAAAAAAAAAAAVbgK
AGN1c3RvbVhtbC9fcmVscy9pdGVtMy54bWwucmVsc1BLAQItABQABgAIAAAAIQCyOUr/vAYAAIIe
AAATAAAAAAAAAAAAAAAAAFy6CgBjdXN0b21YbWwvaXRlbTIueG1sUEsFBgAAAAAhACEAwwgAAHHB
CgAAAA==

--_004_MN2PR13MB3152FA5D970E0F158DF41456D5579MN2PR13MB3152namp_--

Error conditions and messages

Scenario Operation Error code Error message
MIME content malformed, missing POST, PUT 400 Invalid base64 string for MIME content.