Rules of E-mail Addresses

Today, I learned about rules of e-mail addresses.

The form of e-mail addresses is defined by the global common standard called RFC.

If you violated this standard when you created your address, the address would not be used properly.

The basic four rules are the following:

・You have to put an alphabet or a number just prior to '@ (at sign).'

・You have to use an alphabet as the first character of your address.

・You must not use two or more dots(.) or underscores(_) continuously.

・You must not use the signs like / ! “@ # $ % & ‘ ( ) = ~ | \ ^ : ; * + ? < > , ` [ ] { }

However, if you try to create a violated e-mail address, the recent system will alert the violation and you can't create the address.

Therefore, there is no need to worry about these rules.