How should I write an email address? Are capitals OK?

[EC]

How should I write an email address? Are capitals OK?

An email address consists of:

username + @ + domain name

You can write an email address with CAPITAL LETTERS or with small letters, or with a mixture of the two. For example, JustAnExample@SITE543.COM and justanexample@site543.com are the same.

Email addresses can contain:

letters of the English alphabet
numbers 0-9
hyphens -
underscore _
dots .
plus of course the mandatory at sign @

You cannot use spaces.

For example, all the following would be possible:

justanexample@site543.com
JustAnExample@SITE543.COM
just-an-example@Site543.com
just.an.example@site543.com
just_an.example-99@SITE543.COM