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Posteo vs Fastmail: catalog facts
Posteo	Fastmail
Paid 1 euro per month, with paid upgrades for storage and aliases.	Paid Paid subscription with a 30-day free trial that needs no credit card.
Web	Android, iOS, Web
Signup without personal details Low fixed monthly price	Email, calendar and contacts in one service Choice of EU or USA data residency
No free tier 4 GB base storage	No free plan after the trial Hosted service, so your mail lives on Fastmail's servers
Web application, Hosted service	Downloadable app, Web application, Hosted service
Closed source	Closed source
License not stated	License not stated
Account needed	Account needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Checked September 23, 2026	Official website Full listing and sources Checked September 23, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.