Concept
Advanced analytics
Read the seven Advanced analytics charts, from SMTP response codes to time to inbox and delivery by provider, and use them to diagnose delivery problems.
The Advanced tab of Email APIAnalytics is for working out why delivery changed, not only that it changed. Its charts break delivery down by final status, by the reply codes receiving servers sent, by speed and by mailbox provider. It’s available on Pay as you goProBusinessCustom.
The tab uses the same Sending domain, API key and date range controls as the rest of Analytics, and you can rearrange, resize, add and remove its widgets the same way as on the Dashboard tab. Every widget’s View details opens a larger chart with a breakdown table.
The charts
Emails by status
A stacked chart of outgoing emails created in each period, by the status they ended with: Delivered, Bounced, Failed, Rejected, Suppressed, Complained and Canceled. Emails that were opened or clicked count as Delivered on the chart; View details lists Loaded and Clicked separately.
Emails still in progress (accepted, scheduled or attempted) and held emails aren’t shown, so the most recent periods can look smaller until delivery finishes.
Delivery response statuses
A bar chart of the SMTP reply codes from delivery attempts, for example 250 for accepted, 421 or 451 for “try later”, and 550 for a rejected mailbox. The eight most common codes are shown, and the rest are grouped as Other. Each delivery attempt counts once, so one email that was retried three times adds three codes.
4xx and 5xx delivery errors
A stacked chart of delivery attempts that got an error code: 4xx (temporary, Emailit retries) and 5xx (permanent, the email bounces). A rise in 4xx means receiving servers are deferring you; a rise in 5xx means they’re refusing you.
Time to inbox
Three lines for successful deliveries: Average, p50 (median) and p95. It measures how long the successful delivery attempt took, from starting the SMTP conversation to the receiving server accepting the message. Time spent waiting in the queue or between retries isn’t included. View details shows how many deliveries fell into each duration bucket, from under 1 second to over 5 minutes.
Loads and clicks
Total opens and clicks over time, counting every load and click, by when it happened. It needs tracking on your sending domains. Apple Mail Privacy Protection and similar features load images automatically, so treat loads as a trend rather than an exact count of readers.
Failed, rejected, suppressed
A stacked chart of emails that ended without a delivery attempt or with a processing error. Suppressed emails were sent to addresses on your suppression list, Rejected emails were blocked because the workspace wasn’t verified, and Failed emails hit an error. See Email statuses.
Delivery by provider
Delivery rate over time for each recipient mailbox provider: delivered, opened or clicked emails divided by emails sent. Providers are detected from the recipient’s domain:
| Provider | Domains |
|---|---|
| Gmail | gmail.com, googlemail.com |
| Outlook | outlook.com |
| Live | live.com |
| Hotmail | hotmail.com |
| Yahoo | yahoo.com, ymail.com, rocketmail.com and other yahoo.* domains |
| iCloud | icloud.com, me.com, mac.com |
| Other | Everything else |
Business mailboxes hosted by Google Workspace or Microsoft 365 use their own domains, so they count as Other. View details lists sent, delivered, bounced, opened and clicked counts per provider.
Diagnose common problems
| What you see | What it usually means | What to do |
|---|---|---|
Bounced grows in Emails by status, with more 550 codes and a 5xx rise |
You’re sending to addresses that don’t exist, for example from an old or purchased list. | Filter by Sending domain or API key to find the source, open Email APIEmails filtered by status bounced to see the replies, and clean the list. Email verification helps before large sends. |
4xx errors and 421 or 451 codes rise, and p95 time to inbox climbs |
A provider is throttling you, often after a sudden jump in volume or on a new domain or IP. | Check which provider drops in Delivery by provider. Spread sends over time and warm up new domains. |
| One provider’s delivery rate drops while others are steady | That provider is filtering or rejecting you specifically. | Check SPF, DKIM and DMARC on the domain, read the replies on bounced emails to that provider, and see Best practices. |
| Suppressed grows | Your code keeps sending to addresses that bounced or complained before. | Check suppressions before sending, or remove addresses from your own lists. See Suppressions. |
| Rejected appears | The workspace isn’t verified and emails went to non-members. | Request production access. |
| Delivered is steady but loads and clicks fall | Messages may be landing in spam, or tracking stopped working. | Check that the tracking domain is still verified and review spam checks on recent emails. |
| Complaints rise | Recipients don’t expect or want the mail. | Make unsubscribing easy, send only to people who opted in, and watch the Complaint rate card on the Dashboard tab. |
When a chart points to a problem, go from the trend to individual emails: filter Email APIEmails by the same domain, status and dates, and read the Deliveries tab of a few affected emails.