Mailbox-based sending, operated like infrastructure.
Connect Gmail or Google Workspace SMTP, stay within Google's sending policies, and get the orchestration layer that individual mailboxes cannot give you on their own.
- SMTP & App Password
- WorkspaceSMTP & App Password
- Quotas
- Per-mailboxQuotas
- Reporting
- UnifiedReporting
- With ESPs
- PooledWith ESPs
Mailbox SMTP has limits. Orchestration makes them manageable.
Gmail and Google Workspace mailboxes can send through SMTP with App Passwords or OAuth-based credentials. Google enforces clear daily send limits per user, and those limits exist for reputation reasons — we respect them.
Mailers.io lets you operate mailbox-based sending like real infrastructure: per-mailbox quotas, clean suppression, templates, reporting, and safe failover to ESP-backed pools when limits are reached. We do not encourage or support behaviour that breaks Google's terms of service.
From individual mailboxes to a managed sending pool.
- Step 1
Attach mailbox credentials
Add SMTP host, port, username, and App Password (or equivalent). Each mailbox becomes its own sending server.
- Step 2
Set realistic quotas
Cap each mailbox within Google's documented limits. Mailers.io never pushes past the cap you set.
- Step 3
Route & monitor
Use mailbox pools for low-volume, relationship-style sends. Fall through to ESP-backed pools for higher-volume workflows.
What the platform adds around mailbox sending.
Per-mailbox isolation
Each mailbox is a distinct sending server. Quota, reporting, and auth live at the mailbox level.
Quota enforcement
Platform respects per-user daily sending limits. No silent overage, no blind bursts.
Pool with ESP-backed routes
Combine mailbox sending (low volume, personal) with ESP-backed routes (higher volume) in one strategy.
Shared templates & suppression
Unsubscribe and DNC enforcement apply to mailbox-based sends the same as every other route.
Unified reporting
See every mailbox send alongside ESP sends, with provider attribution and response codes.
Policy-safe defaults
We do not bypass Google policy. Accounts that appear to violate TOS are throttled and flagged.
- Low-volume, human-looking outbound (sales follow-ups, partner outreach)
- Small teams that want unified reporting across mailboxes
- Operators who need mailbox sending alongside ESP pools — not instead of them
- Use cases that fit comfortably inside Google Workspace limits
- Daily sending limits are Google's, not ours — we will not exceed them
- High-volume outbound should go through ESPs, not mailboxes
- App Passwords or approved auth mechanisms are required; we do not encourage workarounds
- Using mailbox sending for spam violates Google TOS and is not supported
Questions answered clearly.
Use mailboxes where they fit. Use ESPs where they do not.
Pool Workspace mailboxes with ESP-backed sending servers and get realistic quotas, unified reporting, and policy-safe routing.