Guides
Own Your Email Identity: Why a Domain Makes Your Address Portable
An address on a domain you control keeps working when you change mailbox providers. An address on someone else's domain does not.
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Privacy
Signing Up for New Services: Aliases, Plus Addressing and Unique Passwords
Address hygiene when registering for services: plus addressing, aliases and unique passwords, so one leak does not expose everything you use.
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Operations
Greylisting Explained: How It Works, Its Benefits and Its Delays
Greylisting temporarily rejects unknown senders and accepts them on retry. It stops much bulk spam with little overhead, at the cost of a delay for first.
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Privacy
Why Short Log Retention Is a Privacy Control
Logs help operators run mail reliably, but they also record who talked to whom and when. Here is which operational logs a mail service needs and why keeping.
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Encryption
Protected Headers and Encrypted Subjects in PGP and S/MIME Mail
Standard PGP and S/MIME encrypt the body but leave the subject visible to every server on the path. Protected headers move the subject inside the encrypted.
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Encryption
Planning for Lost PGP Keys: Revocation Certificates and Backups
A lost PGP private key cannot be recovered by a provider. Plan ahead with a revocation certificate, an encrypted backup and a restore procedure you have.
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Privacy
Email Hygiene for Sensitive Work
Practical habits for people who handle sensitive information by email, covering what to leave out, how to address and share, and how to clean up after yourself.
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Threats
How business email compromise works and how to stop it
How business email compromise works, why authenticated mail still gets through, and the controls that stop payment and data fraud.
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Encryption
Autocrypt and Opportunistic Encryption: The Tradeoffs
Autocrypt exchanges OpenPGP keys in ordinary email headers to enable opportunistic encryption, and what that convenience costs in trust.
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Threats
Why You Should Never Email a Password
Email keeps copies of a password in many places it cannot be recalled from. Here is where a sent password ends up, why transport encryption does not solve it.
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Operations
Reverse DNS and IP Reputation: PTR Records and Deliverability
Receiving servers judge a sending IP by its reverse DNS, its forward confirmation and its history. Here is how to check each one.
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Guides
Catch-All Addresses: Pros and Cons
A catch-all mailbox accepts mail for any name on a domain. It removes friction and adds spam, backscatter and filtering work.
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