A conformant email client is minimally required to support the “mixed” and “digest” subtypes. Other commonly used subtypes are “alternative”, “message”, “related”, “report”, “signed”, “encrypted”. Note that many of these subparts can be nested.
The example patterns below are emails composed on the listed email clients filtered with of the courier reformime utility. This makes the structure more human-readable.
$ cat test.eml | reformime -i | egrep 'content-|section'| Pattern | Outlook 2010 | OSX Mail v4.6 | Android Gmail v4.2.1 | Android Email v4.1 | iOS Mail |
|---|---|---|---|---|---|
| plain text |
section: 1
content-type: text/plain
content-transfer-encoding: 7bit
content-language: en-us
|
section: 1
content-type: text/plain
content-transfer-encoding: 7bit
|
section: 1
content-type: text/plain
content-transfer-encoding: base64
|
section: 1
content-type: text/plain
content-transfer-encoding: 7bit
|
|
| rich text |
section: 1 content-type: multipart/alternative content-transfer-encoding: 8bit content-language: en-us section: 1.1 content-type: text/plain content-transfer-encoding: 7bit section: 1.2 content-type: text/html content-transfer-encoding: quoted-printable |
section: 1
content-type: multipart/alternative
content-transfer-encoding: 8bit
section: 1.1
content-type: text/plain
content-transfer-encoding: 7bit
section: 1.2
content-type: text/html
content-transfer-encoding: 7bit
|
section: 1
content-type: multipart/alternative
content-transfer-encoding: 8bit
section: 1.1
content-type: text/plain
content-transfer-encoding: 8bit
section: 1.2
content-type: text/html
content-transfer-encoding: 8bit
|
||
| attachment |
section: 1
content-type: multipart/related
content-transfer-encoding: 8bit
content-language: en-us
section: 1.1
content-type: multipart/alternative
content-transfer-encoding: 8bit
section: 1.1.1
content-type: text/plain
content-transfer-encoding: 7bit
section: 1.1.2
content-type: text/html
content-transfer-encoding: quoted-printable
section: 1.2
content-type: image/jpeg
content-name: image001.jpg
content-transfer-encoding: base64
content-id: <image001.jpg@01CDF571.231AA230>
|
section: 1 content-type: multipart/mixed content-transfer-encoding: 8bit section: 1.1 content-type: text/plain content-transfer-encoding: 7bit section: 1.2 content-type: image/jpg content-name: tiny_image.jpg content-transfer-encoding: base64 content-disposition: inline content-disposition-filename: tiny_image.jpg |
section: 1
content-type: multipart/mixed
content-transfer-encoding: 8bit
section: 1.1
content-type: multipart/alternative
content-transfer-encoding: 8bit
section: 1.1.1
content-type: text/plain
content-transfer-encoding: 8bit
section: 1.1.2
content-type: text/html
content-transfer-encoding: 8bit
section: 1.2
content-type: image/jpeg
content-name: IMG_20130106_203051.jpg
content-transfer-encoding: base64
content-disposition: attachment
content-disposition-filename: IMG_20130106_203051.jpg
|
section: 1
content-type: multipart/mixed
content-transfer-encoding: 8bit
section: 1.1
content-type: text/plain
content-transfer-encoding: base64
section: 1.2
content-type: image/jpeg
content-name: 12 - 1
content-transfer-encoding: base64
content-disposition: attachment
content-disposition-filename: 12 - 1
|
|
| multiple forwarded messages |
section: 1
content-type: multipart/mixed
content-transfer-encoding: 8bit
content-language: en-us
section: 1.1
content-type: multipart/alternative
content-transfer-encoding: 8bit
section: 1.1.1
content-type: text/plain
content-transfer-encoding: 7bit
section: 1.1.2
content-type: text/html
content-transfer-encoding: quoted-printable
section: 1.2
content-type: message/rfc822
content-transfer-encoding: 7bit
content-disposition: attachment
section: 1.2.1
content-type: text/plain
content-transfer-encoding: 7bit
content-language: en-us
section: 1.3
content-type: message/rfc822
content-transfer-encoding: 7bit
content-disposition: attachment
section: 1.3.1
content-type: text/plain
content-transfer-encoding: 7bit
content-language: en-us
|
section: 1 content-type: multipart/mixed content-transfer-encoding: 8bit section: 1.1 content-type: message/rfc822 content-name: Welcome content-transfer-encoding: 7bit content-disposition: attachment content-disposition-filename: Welcome section: 1.1.1 content-type: multipart/mixed content-transfer-encoding: 8bit section: 1.1.1.1 content-type: multipart/alternative content-transfer-encoding: 8bit section: 1.1.1.1.1 content-type: text/plain content-transfer-encoding: 7bit section: 1.1.1.1.2 content-type: text/html content-transfer-encoding: 7bit section: 1.1.1.2 content-type: text/html content-transfer-encoding: 7bit section: 1.2 content-type: message/rfc822 content-name: free trial content-transfer-encoding: 7bit content-disposition: attachment content-disposition-filename: free trial section: 1.2.1 content-type: multipart/mixed content-transfer-encoding: 8bit section: 1.2.1.1 content-type: multipart/alternative content-transfer-encoding: 8bit section: 1.2.1.1.1 content-type: text/plain content-transfer-encoding: 7bit section: 1.2.1.1.2 content-type: text/html content-transfer-encoding: 7bit section: 1.2.1.2 content-type: multipart/alternative content-transfer-encoding: 8bit section: 1.2.1.2.1 content-type: text/plain content-transfer-encoding: 7bit content-id: <4fe888e9a7b3_318df1213836448@domU-12-31-39-05-28-B1.mail> section: 1.2.1.2.2 content-type: text/html content-transfer-encoding: 7bit content-id: <4fe888e9b5a1_318df121383652f@domU-12-31-39-05-28-B1.mail> |