Most issues fall into one of three buckets: deliverability (hard bounces, complaints), scheduling (cancelling a campaign before it goes out), or contact state (why isn't this person receiving emails). Here's how to identify and resolve each.
Cancelling a scheduled campaign
A scheduled campaign can be cancelled at any time before its scheduled send time. Open the campaign and click "Cancel schedule." The campaign moves back to Draft and the scheduled time is cleared. You can re-schedule it or edit and reschedule.
Once a campaign has started sending, it cannot be cancelled. There's no "stop send" button mid-flight.
Hard bounces — automatic suppression
A hard bounce means the email permanently failed to deliver — invalid address, blocked recipient, or a few other terminal conditions. When a hard bounce comes back, the system automatically adds the contact to the suppression list and sets their status to "bounced." They won't receive any further sends, including automations they're currently enrolled in (those runs are cancelled).
You'll see hard-bounced contacts in the contacts list with a "Bounced" status badge. To re-enable a contact (e.g., if you confirmed they have a working address), remove them from the suppression list manually.
Soft bounces — temporary failures
A soft bounce is a temporary failure: the inbox is full, the receiving server is down, or DNS is misconfigured on the recipient's side. Soft bounces are logged but do NOT automatically suppress the contact. The system will try again on future sends.
Spam complaints
When a recipient marks an email as spam, the complaint comes back through Postmark (or SES) and the system updates the contact's status to "complained" and adds them to suppression. As with bounces, complained contacts are cancelled from any in-flight automations.
There's no manual override for spam complaints — once a contact has complained, they cannot be sent to again without going through the standard re-opt-in process.
Unsubscribes
Every email includes an unsubscribe link. Clicks are processed immediately: the contact's status changes to "unsubscribed" and they're removed from any automations they were in. Unsubscribes are separate from suppression — both prevent future sends, but unsubscribe is the legally-required recipient-initiated action; suppression is automatic, system-initiated.
What is not available
A/B subject line testing is not supported. Each campaign has a single subject line.
Image alt text editing is not exposed in the Unlayer-based email editor.
There is no time-based cancellation cutoff (e.g., "can only cancel within X hours") — scheduled campaigns can be cancelled any time before send.
Frequently Asked Questions
I cancelled a scheduled campaign but it still sent — why?
Most likely the campaign had already started sending when you clicked Cancel. Cancellation only works while the campaign is in Scheduled status. Once it transitions to Sending, the send is in motion and cannot be stopped.
A contact says they're not getting my emails but I see no bounce or complaint — what do I check?
Look at their contact status. If it's Unsubscribed, Bounced, or Complained, that's the reason. If status is Active, check whether the contact is on a suppression list separately. If everything looks fine, the issue is on their side (spam folder, mail rule, server-side filtering at their employer).
Why don't I see an A/B test option?
Because A/B subject testing isn't built. Each campaign has one subject. If you want to test variants, send two separate campaigns to halved audiences and compare manually.
Related guides
Marketing Plans and Usage
Three tiers: Individual (free, 125 emails/month), Growth ($4 per 1,000-email block over 1,000), and Pro ($3 per 1,000-email block over 5,000). Quotas reset at the start of each calendar month.
Marketing Automations
Per-contact email workflows that fire on a specific trigger and walk each contact through a fixed sequence of steps. Built for "if this happens, send these emails" use cases — not for conditional branching.
Sending Domains and DNS Setup
Verify a custom domain so marketing emails come from your address ([email protected]) with proper SPF, DKIM, DMARC, and Return-Path records.