When creating an email account, for example with Microsoft Exchange, the following rules can be used to avoid creating invalid email addresses.
These rules apply to the ‘local’ part of the email address, that is local@domain.tld
- Use only alphanumeric characters. That is, use only “A” through “Z” and “0 (zero)” through “9”.
- Do not use the following characters: < > ( ) [ ] ; : , @ \
- As long as they are not the first character in the e-mail address, hyphens ( – ), underscores ( _ ), periods ( . ), and numeric characters (“0” through “9”) are acceptable characters to use within the address.
For example:
| Correct | Incorrect | Why? |
| [email protected] | –[email protected] | Starts with a non-standard character |
| [email protected] | _[email protected] | Starts with a non-standard character |
| [email protected] | .[email protected] | Starts with a non-standard character |
- Do not use null characters (spaces) between characters. However, as mentioned above, underscores are acceptable.
For example:
| Correct | Incorrect | Why? |
| [email protected] |
janwa [email protected] |
Has space within email address |