Alias

An address created here that forwards to you. orders.4kf2@skudo.org is an alias. You can have many, and they cost nothing.

Recipient

The real address an alias forwards to. Yours, added and verified once. See Choosing where your mail is forwarded.

Local part

The bit before the @. In orders.4kf2@skudo.org the local part is orders.4kf2.

Shared domain

A domain we run and everybody uses, for example skudo.org. Reputation on it is shared, which is why new addresses on it are rate limited.

Personal subdomain

anything@yourname.skudo.org, yours alone. Less recognisable from the outside than the bare shared domain, so the monthly limit on it is higher.

Custom domain

A domain you own and point at us with four DNS records. No monthly alias limit, and addresses on it say nothing about the service carrying them.

Catch-all

The setting that makes an address exist the first time somebody writes to it, instead of requiring you to create it first. See Addresses you never created.

Bounce

A message from a mail server saying delivery failed. It carries a code that says whether the failure is permanent. See Reading a bounce.

SPF, DKIM, DMARC

Three DNS records that let other providers tell whether mail claiming to be from a domain really came from a server allowed to send for it. They are why forwarded mail reaches an inbox instead of a spam folder. Explained in The four records, and what each one does.

PGP

An encryption standard. If you give us your public key, we encrypt each message before forwarding it, so that what leaves our servers can only be opened by you. See Encrypted forwarding with PGP.

Quarantine

A middle state between delivered and blocked: the message is held rather than forwarded, so you can look at it before deciding. A rule can put a message there.