The three most-used ChatGPT alternatives — Google Gemini, Anthropic Claude, and Perplexity — each handle email-based identity differently, but the practical outcome with disposable addresses is similar across all of them: expect to be blocked, and plan around it rather than through it.
Google Gemini
Gemini requires a Google account. Google does not allow creating a new account with a disposable email domain — the registration form rejects known disposable domains before a verification email is sent. Beyond the domain check, new Google accounts frequently require phone verification as a second step. For occasional Gemini access, sign in with a Google account you already own.
Anthropic Claude
Claude uses a magic-link or email-code authentication model: every sign-in on a new device sends a login code to the address on file. This means the email is not a registration formality — it is the active authentication credential every time you return. Anthropic filters known disposable domains at signup. Any domain that slips through becomes a problem the next time you need to sign in from a new device and the inbox no longer exists.
Perplexity
Perplexity also supports magic-link sign-in and similarly relies on the email being reachable at each future login. Its disposable-domain blocklist is updated regularly, so an address that worked last month may be rejected next month. Some lesser-known disposable domains still slip through, but with no guarantee of longevity.
Why all three block disposable addresses
The free tiers of these services — Gemini Advanced trials, Claude's free message quota, Perplexity Pro trials — each have real monetary value. Disposable email makes it trivial to claim those tiers repeatedly, which is the specific behaviour these blocklists are designed to prevent. The lists are actively maintained rather than static, so the window of any particular domain working is shrinking.
What to do instead
An email alias that forwards to your real inbox — from SimpleLogin, AnonAddy, Apple's Hide My Email, or your mail provider's alias feature — is accepted by all three services and keeps their marketing email isolated and disableable. For Gemini specifically, a secondary Google account works cleanly if you have one.