Open rate goes up when three things line up: the right person, the right inbox, and a subject line worth opening. If even one of the three breaks, the rate falls. Fix them in that order.

Order matters: Don’t spend a week A/B testing subject lines if half your sends land in spam. Fix deliverability first, list quality second, then iterate on subject lines.

Step 1 — Land in the inbox

Authenticate your domain (SPF, DKIM, DMARC), keep complaint rate under 0.1% and avoid common spam triggers. See avoid the spam folder and avoid anti-spam filters.

Step 2 — Send to people who want it

Confirmed opt-in lists open more than scraped or bought ones. Remove inactive subscribers (no open in 6 months) so your engaged audience defines your sender reputation. Quality beats quantity every single time.

Step 3 — Win the open with the subject line

Lead with value, keep it under 50 characters, match the body. Pair it with a strong preheader. Practical guides: tips for an email subject line, subject line length, and the AI subject line generator.

Step 4 — Personalize and segment

Personalized subjects open more, but only when personalization adds information. Combine with simple segmentation (active vs. inactive, by interest tag, by city). See email personalization tips.

Step 5 — Send at the right time

  • Time of day — Test 8–10 AM and lunch slots
  • Day of week — Tuesday/Wednesday for B2B, weekends for B2C
  • Frequency — Cut sends if open rate drops two campaigns in a row
  • Cadence per subscriber — Pause sends after 3 unopened emails in a row

Measuring progress

Track the moving average of opens, not single sends. See opening rate statistics and the metric definition on opening rate.

Boost opens in three weeks

Week 1: fix authentication and clean inactives. Week 2: rewrite subject lines and add a preheader. Week 3: A/B test send time. Re-measure your open rate at the end of week 3.

Previous question

   

Next question

You might also be interested in:

Why I Should Migrate My Emails to Contacts?

The legacy address-book system stores names and emails — full stop. The new Contacts system stores names, emails, custom fields,...

Read more

How can I increase my opening rate?

Open rate goes up when three things line up: the right person, the right inbox, and a subject line worth...

Read more

What is the click-through rate (CTR)?

The click-through rate (CTR) is one of the most important KPIs in email marketing. It measures the share of recipients...

Read more

Can I increase the monthly credits number?

Yes — you can raise your monthly credit volume at any time from your Mailpro account. No interruption, no extra...

Read more

How Can I Migrate My Emails to Contacts?

If you’ve been using Mailpro for a while, you may still have some address books in the legacy «email lists»...

Read more

Unleash the Power of Professional Email Marketing

Secure, scalable, and built for impact. Join Mailpro™ today and enjoy 500 free credits to send your first campaign.
Start Sending for Free