How often each ESP's mail arrives late, measured from the sending server to the inbox (parsed from message headers). Ranked within each group by the share taking 5+ minutes — split by the kind of customer each platform serves, so big-sender tools aren't compared against small-business ones.
Delays usually mean the receiver is throttling or greylisting the sender.
Built for large senders — Salesforce Marketing Cloud, Braze, Iterable, Adobe Campaign, and similar.
| ESP | Emails | Delay mix | Slow | Very slow | Severe |
|---|---|---|---|---|---|
| 981 | 14% | 14% | 0 | ||
| 4,735 | 11% | 9.8% | 0.3% | ||
| 849 | 1.9% | 2.2% | 0 | ||
| 1,133 | 1.2% | 1.0% | 0 | ||
| 973 | 0.5% | 0.9% | 0 | ||
| 1,003 | 1.5% | 0.8% | 0 | ||
| 5,038 | 1.1% | 0.5% | 0 | ||
| 2,402 | 0.2% | 0.3% | 0 |
Aimed at small and mid-size senders — Mailchimp, Klaviyo, Brevo, HubSpot, and similar.
| ESP | Emails | Delay mix | Slow | Very slow | Severe |
|---|---|---|---|---|---|
| 2,754 | 12% | 4.6% | 0.1% | ||
| 1,374 | 1.2% | 4.2% | 0.4% | ||
| 3,788 | 3.9% | 2.5% | 0.1% | ||
| 892 | 3.0% | 1.7% | 0.2% | ||
| 1,090 | 0.3% | 1.3% | 0.4% | ||
| 1,064 | 0.8% | 1.2% | 0.4% | ||
| 1,742 | 5.2% | 1.5% | 0.1% | ||
| 658 | 4.9% | 0.9% | 0 | ||
| 7,002 | 2.0% | 0.6% | <0.1% | ||
| 667 | 0.4% | 0.6% | 0 | ||
| 1,452 | 0.2% | 0.5% | 0 | ||
| 3,604 | 3.4% | 0.4% | 0 | ||
| 1,466 | 0.4% | 0.2% | 0 | ||
| 2,005 | 0.7% | 0.2% | 0 |
Send-API platforms used by senders of every size — SendGrid, Mailgun, Postmark, Amazon SES, and similar.
| ESP | Emails | Delay mix | Slow | Very slow | Severe |
|---|---|---|---|---|---|
| 2,677 | 1.7% | 3.2% | <0.1% | ||
| 5,556 | 2.1% | 2.3% | 0.1% | ||
| 14,407 | 1.5% | 0.6% | <0.1% | ||
| 1,085 | 0.9% | 0.5% | 0 | ||
| 15,716 | 0.6% | 0.1% | <0.1% |
Based on 94,517 delivery-timed emails (ESPs with 500+ shown). Delay is attributed to each brand's primary ESP, so read it as "mail sent via X arrives slowly this often." Severe (30 min+) is tracked from today onward; older 30-min delays are still counted under very slow.
