Valid Email Domain Name Characters. Period characters are allowed only when they are used to delimit the components of domain style names. There can be up to 48 characters after the symbol.
Uppercase and lowercase letters in English A-Z a-z Digits from 0 to 9 A hyphen - A period used to identify a sub-domain. Without this email domains are not valid. Domain names may be a maximum of 253 characters and consist of.
The domain appears to the right of the symbol.
There can be up to 64 characters before the symbol. When creating an email account for example with Microsoft Exchange the following rules can be used to avoid creating invalid email addresses. Two dots next to each other or a dot at the beginning or end of the local part are not allowed by RFC2822. The total length must not exceed 113 characters.