The presence of the single quotation mark, sometimes referred to as an apostrophe, within the local part of an electronic mail identifier is a subject of technical specifications and practical implementation. For instance, an address might be structured as ‘first.o’last@example.com. However, it’s critical to understand whether mail systems and internet service providers correctly interpret this character.
Acceptance of this character in email identifiers has varied throughout the history of electronic communication. While the applicable Request for Comments (RFC) specifications technically permit its use, many older and even some modern mail transfer agents (MTAs) and validation routines reject addresses containing it. The potential consequence is undelivered mail or bounce-back notifications to the sender. Therefore, reliance on this character in a primary contact address is generally discouraged due to the high risk of incompatibility.
