How We Protect Your Warmup Emails
Your warmup emails are protected by a multi-layered defense system that works around the clock to ensure reliable delivery and safeguard your sender reputation.
Layer 1: Global Domain Blocklist
Our team maintains a curated blocklist of domains that are excluded from the warmup peer pool. If a domain is known to have persistent delivery issues — such as invalid mailboxes, expired accounts, or infrastructure problems — it is blocked system-wide so your warmup emails are never sent to unreliable destinations.
Layer 2: Automatic MX/SMTP Health Checking
A background service runs every 2 hours to verify the DNS records and mail server reachability of every domain in the warmup pool. If a domain's mail server becomes unreachable or stops responding, it is automatically excluded from peer selection. When the domain comes back online and passes health checks again, it is restored automatically — no manual intervention needed.
Layer 3: IMAP Bounce Detection
During regular inbox scanning, the system monitors for bounce-back messages and delivery failure notifications (also known as NDRs). If a particular domain causes 3 or more bounces within a 7-day window, it is automatically added to the blocklist. This catches delayed delivery failures that may pass initial send checks but ultimately fail.
Additional Safeguards:
- Spam Rescue — Warmup emails that land in spam or junk folders are automatically detected and moved back to your inbox, training email providers that your messages are legitimate.
- Cross-Provider Pairing — The system prefers pairing mailboxes across different providers (e.g., Gmail to Outlook) for stronger deliverability signals.
- Health Scoring — Every mailbox receives a health score. Mailboxes with poor scores are excluded from the peer pool to protect other users.
- Pool Depletion Protection — If most peers become temporarily unavailable, the system falls back gracefully rather than blocking your warmup entirely. Your warmup continues with available healthy peers.
All of these protections run automatically in the background. You do not need to configure or manage anything — just enable warmup and the system handles the rest.