Rules

Rules watch your mail stream so you don’t have to. Each rule is a when / if / then sentence — when a mail arrives, if it matches your conditions, then act on it — built visually in the console under Rules. The engine unlocks on Team plans and up, with the full rule vocabulary from Business (Plans & add-ons).

A few real shapes:

• If the subject contains [staging], pause the mail — a seatbelt against test blasts escaping to customers.
• If the recipient domain is gmail.com, route through Amazon SES — provider steering by audience.
• If an attachment is bigger than 10 MB, reject — policy at the gateway instead of in every app.
• If the mail is tagged invoice, BCC the bookkeeping inbox.

Scopes

A rule lives at one of three levels, evaluated in this order:

Scope	Applies to	Managed by
Platform	everyone (Mailway’s own safety rules)	read-only
Team	every project in your team	team admins
Project	one project	admins & developers

Within a scope, rules run in the priority order you set (drag to reorder). A stop action halts the chain for that mail.

When — the trigger

• On receipt — the moment Mailway accepts the mail. Envelope-level facts (sender, recipients, size) are available.
• After parsing — once the message is parsed. Content conditions (subject, body, headers, attachments) match here.

The console picks the right trigger for the conditions you choose.

If — conditions

Condition	Matches on
subject_contains / subject_matches	subject substring / regex
body_contains / body_matches	body substring / regex
from_email_is / from_domain_is	exact sender / sender domain
recipient_email_in / recipient_domain_in / recipient_domain_not_in	recipient allow/deny sets
recipient_count_gt	more than N recipients
header_present / header_value_is	a header exists / equals a value
attachment_count_gt / attachment_filename_matches	attachment count / filename pattern
size_gt / size_lt	message size
tag_present	a tag set by the API or an earlier rule
ingest_type_is / ingest_host_in	how the mail entered (SMTP, API, console) / through which host

Multiple conditions AND together.

Then — actions

On any mail (state and envelope only — the relayed bytes stay untouched):

Action	Effect
pause	hold the mail until someone releases it in the console
reject	stop it permanently, with a reason
route_provider	pin the send to specific provider(s)
tag / untag	label the mail (searchable, echoed on webhooks)
add_bcc	add a blind recipient to the envelope
stop	halt rule processing for this mail

On API-submitted mail only (these modify content, which would break the byte-for-byte promise on relayed SMTP messages):

Action	Effect
add_cc / redirect_to	add a visible recipient / replace all recipients
prepend_subject	prefix the subject, e.g. [STAGING]
add_header / set_reply_to	set a header / the reply-to
inject_unsubscribe	add List-Unsubscribe (+ one-click) headers
generate_text_part	synthesize a text/plain part from the HTML

Note

Rules also power webhooks under the hood — subscribing an endpoint to events creates hidden routing rules, so delivery gets the same reliability machinery.

Observability

Every rule shows its match history — which mails it touched, when, and what each action did. Rule edits are versioned and written to the team’s audit log, so “why was this mail paused?” always has an answer.