Rot mail

You're referring to ROT13, a simple letter substitution cipher that replaces each letter with the letter 13 positions ahead of it in the alphabet. Here's how it works:

• A becomes N
• B becomes O
• C becomes P
• D becomes Q
• E becomes R
• F becomes S
• G becomes T
• H becomes U
• I becomes V
• J becomes W
• K becomes X
• L becomes Y
• M becomes Z
• N becomes A
• O becomes B
• P becomes C
• Q becomes D
• R becomes E
• S becomes F
• T becomes G
• U becomes H
• V becomes I
• W becomes J
• X becomes K
• Y becomes L
• Z becomes M

To encode a message using ROT13, you simply replace each letter with the corresponding letter 13 positions ahead of it in the alphabet. To decode a message, you do the opposite: replace each letter with the corresponding letter 13 positions behind it in the alphabet.

For example, if you want to encode the message "HELLO", you would replace each letter with the letter 13 positions ahead of it, resulting in the encoded message "URYYB".

ROT13 is often used as a simple cipher for obscuring the contents of a message, but it's not a secure method of encryption and can be easily broken by anyone familiar with the cipher.