Mailbox Rotation
Assign multiple mailboxes to a single campaign and WarmySender will automatically rotate between them:
Rotation Modes:
- Round Robin (default) — Selects the mailbox with the fewest sends today. This evenly distributes the load across all mailboxes.
- Random — Randomly selects from available mailboxes each time.
- Weighted — Uses configurable weights per mailbox. A mailbox with weight 3 gets roughly 3x the sends of a mailbox with weight 1.
Mailbox Availability:
A mailbox is only used if ALL of the following are true:
• It is marked 'Active' on the campaign (you can disable individual mailboxes without removing them)
• It is in 'Connected' status (not disconnected or in error state)
• It hasn't exceeded its daily per-campaign soft cap
• It hasn't exceeded its global daily limit (500 emails/day)
• It's not currently rate-limited (in backoff)
• It hasn't exceeded the domain daily limit for the recipient's domain
Per-Mailbox Settings (within a campaign):
- Weight — Controls rotation priority (default: 1)
- Active toggle — Enable/disable without removing
- Daily soft cap — Optional per-campaign limit for this mailbox
Capacity Planning:
The scheduler pre-calculates available capacity per mailbox before scheduling new sends, accounting for already-sent emails and pending/processing jobs.
Best Practice: Use 3-5 mailboxes per campaign to distribute sending volume and reduce risk. Ensure all mailboxes have a good warmup health score (70+) before assigning them.