User's eMail Account

1. Every user can create a maximum of five eMail accounts.
2. The eMail Service provider supported by the system is listed as followings

• Yahoo! Mail
• Gmail
• Windows Live Hotmail

Sending an encrypted eMail

1. When sending an encrypted eMail, only recipients who have SFTS accounts can receive it.
2. This is because encrypted eMail requires recipients' public keys to undergo encryption and only recipients who have SFTS accounts have public keys.

Sending an unencrypted eMail

1. When sending an unencrypted eMail, every recipient will receive it disregard whether she/he has a SFTS account (assuming recipients' eMail addressses entered by sender are correct).

Attachment

1. SFTS supports eMail attachment.
2. The maximum number of attachment supported by SFTS is 8 and the maximum size of each attachment is 25 MB.

eMail Message Format

1. SFTS supports rich-text format message. Common formatting such as bold, underline, italic, etc are available.
2. The formatting is the HTML (HyperText Markup Language) which is understandable by most text editors.
3. The proprietary formatting will not be processed and error message will be shown instead.

eMail Encryption

1. The level of encryption is divided into three levels, they are low, medium and strong.

2. Low level encryption

     - 1024-bit asymmetric encryption + 1 round 512-bit symmetric encryption

3. medium level encryption

     - 1024-bit asymmetric encryption + 3 round 512-bit symmetric encryption

4. strong level encryption

     - 2048-bit asymmetric encryption + 5 round 512-bit symmetric encryption

User's Key Pair

1. Each user will be given two pairs of keys (1 pair of 1024-bit private and public key and 1 pair of 2048-bit private and public key).

2. Public keys will be stored by the system while the private keys will be personally kept by the users.

3. Without the private keys, user can't view eMail's content and send eMail (user can only manage her/his contacts).

eMail Message Category

1. eMail message can be categorized into six major categories (I categorized personally). Please refer picture above for pictorial understanding.

Note

1. eMail with formatted message and attachment(s).

2. eMail with unformatted message and attachment(s).

3. eMail with formatted message but without attachment(s).

4. eMail with unformatted message but without attachment(s).

5. eMail without message but with attachment(s).

6. eMail without message and attachment(s).