Built for deliverability
Every feature is designed to get your emails into the inbox, not the spam folder.
Domain Warming
Build sender reputation gradually with an automated warming engine.
Configurable curve
Set starting volume, daily increment, and max volume. Helio follows your schedule.
Provider distribution
Spread warming emails across Gmail, Outlook, and Yahoo in configurable ratios.
Safety auto-pause
Pauses automatically when bounce rate exceeds 5% or complaints exceed 0.3%.
Visual progress
Charts showing daily volume, bounce rates, and provider distribution.
Contact Management
Import, validate, and segment your contacts at scale.
Smart CSV import
Upload CSV, auto-detect columns, map fields, and import with deduplication.
Email validation
MX record checks, disposable email detection, and format validation.
Tags & segments
Organize contacts with tags. Create segments for targeted campaigns.
Auto-suppression
Contacts are suppressed after hard bounces or spam complaints.
Campaign Sending
Create, test, and send campaigns with confidence.
Template editor
HTML editor with variable support ({{firstName}}) and live preview.
A/B testing
Test subject lines across your audience to find what works.
Scheduled sending
Queue campaigns to send at the optimal time.
Rate limiting
Automatic rate limiting to protect your sender reputation.
Monitoring & Analytics
Full visibility into what happens after you hit send.
Real-time tracking
Sent, delivered, opened, clicked, bounced, complained — all live.
Smart alerts
Warnings when bounce or complaint rates approach danger zones.
Daily charts
Time-series charts to spot trends and issues early.
Provider health
SES reputation score and Mailgun delivery stats per project.