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“Please use a different email”: why some sites refuse addresses

October 12, 2026 · 2 min read

Sometimes a form takes one look at your address and says no. The message rarely explains why, but there are only a few common reasons.

Format rules

Some forms are stricter than the email standards themselves. They may reject:

• the + character used for aliases;
• dots at the start or end of the name, or two dots in a row;
• long names, or newer domain endings the form's checker does not know.

These are form limitations, not judgments about you. A plain name of letters and numbers usually gets through.

Disposable domain lists

Many services check addresses against public lists of temporary email domains. They have understandable reasons:

• They need a way to reach you later, for receipts, security alerts or account recovery.
• Free trials and sign-up bonuses get abused by people creating endless accounts.
• Some industries are required to keep a working contact for each customer.

What to do

• If it is a format problem, try a simpler name without special characters.
• If the site deliberately excludes temporary addresses, respect that and use an address you own. A plus-address alias keeps your main inbox tidy while still letting the account work properly.
• Never use temporary addresses to get around a ban or to claim the same offer repeatedly. It breaks the other site's rules and ours.