Analytics8 min readUpdated September 9, 2026

Open, Click, Bounce, and Complaint Tracking Explained

Understand Zilch Mail’s tracking events, link groups, bounce categories, retry behavior, and automatic suppression controls.

Tracking tells you what happened after a campaign was sent, but each event has limitations. Zilch Mail supports local or custom-domain tracking configuration. Paid plans add hosted open analytics and automatic unsubscribe handling; Max adds hosted click analytics through Redirect My Links. Bounce classification and suppression provide additional delivery signals.

Know what each event means

EventWhat it indicatesImportant limitation
OpenA tracking pixel was requestedImages may be blocked, proxied, or preloaded
ClickA tracked link was followedSecurity scanners and automated tools can also follow links
Hard bounceDelivery failed permanently or the address is invalidClassifiers depend on the provider response and DSN details
Soft bounceDelivery was deferred or temporarily failedA retry may still succeed later
ComplaintA recipient or provider reported unwanted mailTreat as a suppression signal, not an engagement metric

Link groups can rotate or weight destinations across messages. Use them for legitimate experiments or routing, keep the destination set small, and label links clearly. The weighted distribution is useful for comparing destinations, but it does not replace a properly designed A/B test.

Understand hosted tracking by plan

CapabilityAvailabilityWhat it does
Local or custom-domain trackingDesktop configurationUses the tracking endpoint configured in the app
Hosted opens and unsubscribePaid plansRecords hosted open events and processes automatic unsubscribe requests
Redirect My LinksMax and Max YearlyRewrites selected destinations, records clicks, then forwards to the original URL

Handle bounces by category

  • Hard bounces should be suppressed quickly and removed from future sends.
  • Soft bounces can be retried with backoff, but repeated failures should move into suppression or review.
  • Complaints should be suppressed immediately and investigated at the campaign and sender level.
  • Provider webhooks and optional IMAP polling can add bounce signals that were not visible during the send.

Do not optimize for opens alone

Open tracking is an imperfect proxy. A campaign with high opens but rising complaints, unsubscribes, or hard bounces is not healthy.

Build a useful review loop

  1. 1Review delivery, bounce, complaint, unsubscribe, open, and click trends together.
  2. 2Identify whether a problem comes from a sender account, domain, segment, template, or schedule.
  3. 3Apply suppression and adjust the affected audience before the next send.
  4. 4Compare campaign results over time rather than reacting to one isolated event.
  5. 5Export the sending log and results when you need an external review or backup.

Protect tracking data quality

Test the tracking pixel, unsubscribe URL, and any enabled redirects before launch. If you configure your own tracking endpoint, use a domain you control. Hosted plan features use Zilch Mail’s configured tracking service. Expect some events from privacy proxies or scanners, and combine tracking with replies, conversions, bounce data, and recipient preferences.

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