Emailer format

You're referring to the format of an email address!

An email address, also known as an electronic mail address, is a string of characters used to identify a mailbox on a mail server. The format of 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 "local 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 (-).

Examples of valid email addresses:

• [email protected]
• [email protected]
• admin@localhost

Examples of invalid email addresses:

• john [email protected] (space in the local part)
• @example.com (no local part)
• example.com (no @ symbol)

It's worth noting that while the format of an email address is standardized, the rules for what constitutes a valid email address can vary depending on the email service provider or organization.