Multiple recipient message encryption

1. A method comprising:

with a computing system of an e-mail service provider, receiving instructions from a client device of a user to divide content of an e-mail message into a plurality of parts;

with the computing system, generating and assigning alpha-numeric part identifiers to each of the plurality of parts;

with the computing system, encrypting each of the plurality of parts with a different encryption key;

with the computing system, receiving, from the client device of the user, a list of recipients of the e-mail message and access privilege data associated with each recipient in the list, the access privilege data indicating which of the plurality of parts each recipient is authorized to access, wherein each recipient is a group within an organization where each group contains an email list;

with the computing system, transmitting the e-mail message to each of the recipients without creating multiple different e-mail messages for each of the recipients;

with the computing system, transmitting the access privilege data, the different encryption key for each of the plurality of parts, and the part identifier for each of the plurality of parts to a server of a security authority;

with the server, receiving a request from a client device of a recipient from the list of recipients of the email message to decrypt the e-mail message, the request including the part identifiers for the plurality of parts;

with the server, based on the part identifiers and the access privilege data, transmitting to the client device of the recipient an encryption key for a part the recipient is authorized to view and withholding an encryption key for a part the recipient is not authorized to view without notifying the recipient that the encryption key for the part the recipient is not authorized to view is being withheld;

with the server, receiving, from a client device of an additional user to whom the e-mail message has been forwarded, a request for an encryption key for a first part of the plurality of parts from the e-mail message and an encryption key for a second part of the plurality of parts from the email message, the additional user being different from any recipient on the list of recipients; and

in response to determining that the additional user is not authorized to view the first part, based on the access privilege data and the part identifier for the first part, withholding the encryption key for the first part.

2. The method of claim 1 , further comprising:

receiving the e-mail message;

transmitting the e-mail message to each of the plurality of recipients;

receiving the access privilege data, the different encryption key for each of the plurality of parts, and the part identifiers for each of the plurality of parts;

transmitting the access privilege data, the different encryption key for each of the plurality of parts, and the part identifiers for each of the plurality of parts to the security authority.

3. The method of claim 1 , wherein a first part of the plurality of parts is a file.

4. The method of claim 1 , wherein a first part of the plurality of parts is a portion of text within the e-mail message.

5. The method of claim 1 , wherein different recipients have different access privileges to different parts of the e-mail message.

6. The method of claim 1 , wherein for the recipient to access a part of the encrypted e-mail message, obtaining the encryption key for that part from the security authority.

7. The method of claim 6 , wherein the recipient receives the encryption key for that part when the recipient is authorized for that part.

8. A method comprising:

with a server of a security authority, receiving a different encryption key for each of a plurality of parts of an encrypted e-mail message from a computing system of an e-mail service provider, the encrypted e-mail message having a plurality of recipients, wherein each recipient of the plurality of recipients is a group within an organization where each group contains an email list, wherein the plurality of recipients do not receive different encrypted e-mail messages;

with the server, receiving a generated alpha-numeric part identifier for each of the plurality of parts of the encrypted e-mail message;

with the server, receiving access privileges for a first recipient of the plurality of recipients, the access privileges for the first recipient identifying which parts of the encrypted e-mail message the first recipient is authorized to access;

with the server, receiving, from a client device of the first recipient, a request for an encryption key for a first part of the plurality of parts from the encrypted e-mail message and an encryption key for a second part of the plurality of parts from the encrypted email message;

in response to determining, based on the access privileges and the part identifier for the first part, that the first recipient is authorized to view the first part, transmitting to the recipient the encryption key for the first part;

in response to determining, based on the access privileges and the part identifier for the second part, that the first recipient is not authorized to view the second part, withholding the encryption key for the second part;

with the server, receiving, from a client device of an additional user to whom the e-mail message has been forwarded, a request for the encryption key for the first part of the plurality of parts from the encrypted e-mail message and the encryption key for the second part of the plurality of parts from the encrypted email message, the additional user being different from any recipient on the list of recipients; and

in response to determining that the additional user is not authorized to view the first part, based on the access privileges and the part identifier for the first part, withholding the encryption key for the first part.

9. The method of claim 8 , further comprising:

determining, based on the access privileges for the first recipient, that the first recipient is authorized to access the first part; and

sending the encryption key for the first part to the encrypted e-mail message to the first recipient.

10. The method of claim 8 , further comprising, receiving access privileges for a second recipient of the plurality of recipients, the access privileges for the second recipient identifying which parts of the encrypted e-mail message the second recipient is authorized to access, the access privileges for the second recipient being different than the access privileges for the first recipient.

11. The method of claim 10 , further comprising, receiving, from the second recipient, a request for the encryption key for the first part of the plurality of parts from the encrypted e-mail message.

12. The method of claim 11 , further comprising, determining, based on the access privileges for the second recipient, that the second recipient is not authorized to access the first part; and

denying the request from the second recipient.

13. The method of claim 8 , further comprising, receiving a request, from an entity that is not a recipient of the encrypted e-mail message, for the encryption key for the first part of the encrypted e-mail message; and

denying the request from the entity.

14. The method of claim 8 , wherein the first part is a file that is configured as an attachment to the encrypted e-mail message.

15. The method of claim 8 , wherein the first part is a portion of text within the encrypted e-mail message.

16. A method performed by a computing system, the method comprising:

receiving from a client device of a user, a plurality of content parts of an e-mail message;

generating and assigning to each of the plurality of content parts, a part identifier that uniquely identifies one of the content parts with an alpha-numeric value;

associating with each of the plurality of content parts, a different encryption key;

receiving, from the client device of the user, a list of recipients of the e-mail message and access privilege data associated with each recipient of a plurality of recipients in the list, the access privilege data indicating which of the plurality of content parts each recipient is authorized to access, wherein each recipient is a group within an organization where each group contains an email list;

transmitting the e-mail message to a server without sending multiple different e-mail messages to the server;

transmitting the access privilege data, the different encryption key for each of the plurality of content parts, and the part identifier for each of the plurality of content parts to a server of a security authority;

with the server, receiving a request from a client device of a recipient of the list of recipients to decrypt the e-mail message, the request including the part identifier for each of the plurality of content parts;

with the server, based on the part identifier and the access privilege data, transmitting to the client device of the recipient an encryption key for a part the recipient is authorized to view and withholding an encryption key for a part the recipient is not authorized to view;

with the server, receiving another request from a client device of an additional user to whom the e-mail message has been forwarded, the another request including the part identifier for each of the plurality of content parts, the additional user being different from any recipient on the list of recipients; and

with the server, based on the part identifier and the access privilege data, withholding an encryption key for a part the additional user is not authorized to view.

17. The method of claim 16 , further comprising:

with the server, encrypting each of the plurality of content parts using the different encryption key associated with that content part; and

transmitting the e-mail message to the plurality of recipients.

18. The method of claim 16 , further comprising, with the security authority;

receiving the access privilege data, the different encryption key for each of the content parts, and the part identifier for each of the content parts;

receiving, from the client device of the first recipient, a request for an encryption key for a first part of the plurality of content parts from the e-mail message; and

in response to determining that the first recipient is authorized to view the part, providing the first recipient with the encryption key for the first part.