Domain pools and scheduling windows

SendCanyon never blasts a campaign from one mailbox. On the Sending step you select a domain pool — a set of your verified domains and their eligible mailboxes — and the send governor distributes the campaign across it, respecting every cap in the system.

How mailbox selection works

For each queued send, the governor picks a mailbox from the pool by rotation, weighted by remaining capacity: each mailbox's daily limit, minus warmup traffic, minus sends already made today, within its domain's own daily cap. Mailboxes still early in their warmup ramp are skipped entirely. If the whole pool is at capacity, sends wait for the next window rather than exceeding a cap — a campaign is never worth a mailbox.

• One contact always hears from one mailbox for the whole sequence — follow-ups come from the same address that opened the thread.
• Sends are paced with human-like spacing (irregular gaps, no fixed intervals), not fired in bursts.
• Adding mailboxes to a pool mid-campaign increases throughput on the next scheduling pass; removing one reassigns only contacts who haven't been contacted yet.

Scheduling windows

A window defines when sends may happen: days of the week and an hour range, evaluated in each contact's time zone where the contact has one, falling back to the campaign default zone otherwise. The default window is Monday–Friday, 8:00–17:00. A contact in Berlin and a contact in Denver both get their emails mid-morning local time, from the same campaign.

Launch, pause, resume

Launch enqueues the campaign — nothing sends inline, and the first sends land when the first window opens. Pause stops new sends immediately (in-flight messages already handed to a provider still deliver) while replies keep being tracked. Resume picks up exactly where the schedule left off; contacts mid-delay don't get double-sent or skipped. Launch and Resume both open a confirmation listing who will be mailed, taken from the saved audience; if the recipients change before you confirm, SendCanyon refuses and shows you the new list. While a campaign is sending you can add exclusions but not new includes; pause it to change who it includes, and Resume then mails the new audience and cancels pending emails to anyone you removed.