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Greylisting and IP allowlists

Greylisting

Greylisting stops much spam sent by tools that never try twice. With it on, a message from a sender this server has not seen before is answered "try again later" (SMTP 451). Real mail servers try again; after a few minutes the retry is accepted, and that sender is remembered, so their later mail arrives at once.

• Switch it on per domain: on the domain's page, tick Greylist (or corpsuite domain set TEAM DOMAIN greylist:=true). It is off by default.
• What counts as "seen": the sending network (its /24 for IPv4, /64 for IPv6, since big senders retry from another address), the sender and the recipient.
• The times (Mailocity admin panel, Settings → Mail delivery → Greylisting and IP allowlist): how long a first attempt is held (5 minutes), how long after it a retry still counts (24 hours), and how long a sender that passed is remembered (36 days).

The cost: the first message from someone new arrives a few minutes late. Mail from your own users, and mail between mailboxes here, is never greylisted.

IP allowlists

An allowlisted network's mail skips greylisting and spam scoring (but viruses are still refused). Use it for senders you trust whose mail filters get wrong: a partner's servers, a scanner or printer, a forwarder.

• The platform's list (operator, in the same card, or corpsuite greylist set ipAllowlist:=[...]) applies to every team, and its networks' signups also skip the reputation checks (IPQualityScore, blocklists, StopForumSpam).
• A team's list (team admins, IP allowlist on the team's page, or corpsuite ip-allowlist set TEAM items:=[...]) applies to mail to that team's mailboxes.

Entries are addresses (192.0.2.10) or networks (198.51.100.0/24, 2001:db8::/48), at most 500.

API

PATCH /v1/tenants/{tenantId}/domains/{domain} with greylist, GET|PATCH /v1/greylist-settings, GET|PUT /v1/tenants/{tenantId}/ip-allowlist.