Email address format standard

The standard format for an email address is as follows:

localpart@domain

Where:

• localpart is the part of the email address that comes before the @ symbol, also known as the "username" or "mailbox name". It can contain letters, numbers, and special characters, but it must not contain spaces or start with a dot (.) or hyphen (-).
• @ is the "at symbol" that separates the local part from the domain.
• domain is the part of the email address that comes after the @ symbol, also known as the "domain name" or "host name". It can contain letters, numbers, and special characters, but it must not contain spaces or start with a dot (.) or hyphen (-).

Here are some examples of valid email addresses:

• [email protected]
• [email protected]
• [email protected]
• [email protected]

And here are some examples of invalid email addresses:

• john [email protected] (spaces are not allowed)
• [email protected] (domain cannot start with a dot)
• [email protected] (local part cannot start with a hyphen)
• john.doe@example (domain cannot be missing)

It's worth noting that while the above format is the standard, some email providers may have their own specific requirements or restrictions on email addresses. Additionally, some characters may be allowed or disallowed by certain email clients or servers, so it's always a good idea to check with the recipient's email provider if you're unsure.