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 |
|---|---|---|---|---|---|
| 1,004 | 14% | 14% | 0 | ||
| 4,838 | 11% | 9.8% | 0.4% | ||
| 865 | 1.8% | 2.3% | 0 | ||
| 1,004 | 0.5% | 0.9% | 0.2% | ||
| 1,141 | 1.2% | 1.0% | 0 | ||
| 1,010 | 1.5% | 0.8% | 0 | ||
| 5,128 | 1.1% | 0.5% | 0 | ||
| 2,473 | 0.2% | 0.3% | <0.1% |
Aimed at small and mid-size senders — Mailchimp, Klaviyo, Brevo, HubSpot, and similar.
| ESP | Emails | Delay mix | Slow | Very slow | Severe |
|---|---|---|---|---|---|
| 2,813 | 12% | 4.6% | 0.1% | ||
| 1,382 | 1.2% | 4.2% | 0.4% | ||
| 3,856 | 3.8% | 2.6% | 0.1% | ||
| 895 | 3.0% | 1.7% | 0.2% | ||
| 1,114 | 0.3% | 1.3% | 0.4% | ||
| 1,064 | 0.8% | 1.2% | 0.4% | ||
| 1,706 | 4.9% | 1.1% | 0 | ||
| 664 | 4.8% | 0.9% | 0 | ||
| 7,131 | 2.0% | 0.6% | <0.1% | ||
| 676 | 0.4% | 0.6% | 0 | ||
| 1,472 | 0.2% | 0.5% | 0 | ||
| 3,675 | 3.5% | 0.4% | 0 | ||
| 1,486 | 0.4% | 0.2% | 0 | ||
| 2,060 | 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 |
|---|---|---|---|---|---|
| 2,694 | 1.7% | 3.2% | 0.1% | ||
| 5,684 | 2.1% | 2.3% | 0.1% | ||
| 14,843 | 1.5% | 0.7% | <0.1% | ||
| 1,113 | 0.9% | 0.4% | 0 | ||
| 15,921 | 0.6% | 0.1% | <0.1% |
Based on 96,292 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.
