Applies to: Exchange Server 2013, Exchange Online
Topic Last Modified: 2012-10-03
Content transfer encoding defines encoding methods for transforming binary email message data into the US-ASCII plain text format. This transformation allows the message to travel through older SMTP messaging servers that only support messages in US-ASCII text. Content transfer encoding is defined in RFC 2045. The transfer encoding method is stored in the Content-Transfer-Encoding header field in the message. In Microsoft Exchange Server 2013, the following content transfer encoding methods are available:
- 7-bit This value indicates that the
message body data is already in the US ASCII plain text format, and
no message encoding has been done to the message.
- Quoted-printable (QP) This encoding
method uses printable US-ASCII characters to encode the message
body data. If the original message text is mostly US-ASCII text, QP
encoding gives somewhat readable and compact results. By default,
Exchange 2013 uses QP for encoding binary message data.
- Base64 This encoding method is based
primarily on the privacy-enhanced mail (PEM) standard defined in
RFC 1421. Base64 encoding uses the 64-character alphabet encoding
method and output padding characters defined by PEM to encode the
message body data. Base64 encoding creates a predictable increase
in message size and is optimal for binary data and non-US-ASCII
text.
You configure the transfer encoding method using the ByteEncoderTypeFor7BitCharsets parameter on the Set-OrganizationConfig and Set-RemoteDomain cmdlets. The content transfer encoding settings you configure with Set-OrganizationConfig apply to all messages in the Exchange organization. The content transfer encoding settings you configure with Set-RemoteDomain apply only to message sent to external recipients in the remote domain.
The following table lists the values that you can use to set the transfer encoding method.
| Parameter in Set-OrganizationConfig | Parameter in Set-RemoteDomain | Description |
|---|---|---|
|
0 |
|
Always use 7-bit encoding for HTML and for plain text. This is the default value. |
|
1 |
|
Always use QP encoding for HTML and for plain text. |
|
2 |
|
Always use Base64 encoding for HTML and for plain text. |
|
5 |
|
Use QP encoding for HTML and for plain text unless line wrapping is enabled in plain text. If line wrapping is enabled, use 7-bit encoding for plain text. |
|
6 |
|
Use Base64 encoding for HTML and for plain text, unless line wrapping is enabled in plain text. If line wrapping is enabled in plain text, use Base64 encoding for HTML, and use 7-bit encoding for plain text. |
|
13 |
|
Always use QP encoding for HTML. Always use 7-bit encoding for plain text. |
|
14 |
|
Always use Base64 encoding for HTML. Always use 7-bit encoding for plain text. |
For more details about Content-Transfer-Encoding header field, see the "Understanding the structure of email messages" section in Content Conversion.
For more information about remote domains, see Remote Domains.
What do you need to know before you begin?
- Estimated time to complete: 15 minutes
- You need to be assigned permissions before you can perform this
procedure or procedures. To see what permissions you need, see the
"Transport service" entry in the Mail Flow
Permissions topic.
- For information about keyboard shortcuts that may apply to the
procedures in this topic, see Keyboard Shortcuts in
the Exchange Admin Center.
 Tip: |
|---|
| Having problems? Ask for help in the Exchange forums. Visit the forums at: Exchange Server, Exchange Online, or Exchange Online Protection |
What do you want to do?
Use the Shell to configure the content transfer encoding method for the organization
To configure the content transfer encoding method for the organization, run the following command:
 Copy Code |
|
|---|---|
Set-OrganizationConfig -ByteEncoderTypeFor7BitCharsets <Integer> |
|
For example, to set the content transfer encoding method to Base64, run the following command:
| Copy Code |
|
|---|---|
Set-OrganizationConfig -ByteEncoderTypeFor7BitCharsets 2 |
|
Use the Shell to configure the content transfer encoding method for a remote domain
To configure the content transfer encoding method for all the recipients in a remote domain, run the following command:
| Copy Code |
|
|---|---|
Set-RemoteDomain -ByteEncoderTypeFor7BitCharsets <Value> |
|
For example, to set the content transfer encoding method to Base64, run the following command:
| Copy Code |
|
|---|---|
Set- RemoteDomain -ByteEncoderTypeFor7BitCharsets UseBase64 |
|
How do you know this worked?
To verify that you have successfully configured the method for content transfer encoding, do the following:
- Send a test message that contains a mixture of US-ASCII text
and binary data or non-US-ASCII text to an internal or external
test account. Use an internal account to test organization
settings, and an external account in the remote domain to test
remote domain settings.
- In an email client, view the Content-Transfer-Encoding
header field in the message, and verify the content transfer
encoding method that was used on the message matches the method you
configured.