If someone were to register a domain like "l’empereur.com" (containing an apostrophe or an accent), the email address "pub@l’empereur.com" would have to be converted into a technical format known as "Punycode" (e.g., "xn--lempereur-...com"). The result:
The user must know the Punycode equivalent for the email to work.
Email software and certain servers do not always handle these formats well.
This complicates daily use—an issue that is particularly problematic for email, where simplicity is essential.
Why choose the simple version?
Universal readability: "lempereur.com" is understood by everyone, without any ambiguity.
Email compatibility: No Punycode conversion is required; the address works everywhere.
Marketing convenience: It is easier to remember, type, and share.
Therefore, the best practice is to simplify to pure ASCII ("lempereur.com") rather than risking potential issues with a domain that includes accents or an apostrophe.