Anti-Abuse & Compliance
Transend sends email over Amazon SES infrastructure. Our sending reputation — and yours — depends on low bounce rates, low complaint rates, and clean sending practices. This page describes the technical and operational controls we use to enforce those standards.
1. Domain verification
Every sending domain must be verified before you can send mail from it. Verification requires adding DNS records to your domain:
- DKIM — a cryptographic signature that proves the email originated from your domain and was not altered in transit.
- SPF — a DNS record that authorises Transend's sending infrastructure to send on behalf of your domain.
- DMARC — a policy that instructs receiving mail servers how to handle messages that fail SPF or DKIM checks, and where to send aggregate reports.
We poll for DNS propagation automatically and notify you in real time if a record is missing or misconfigured. Emails cannot be sent from an unverified domain.
2. Bounce handling
A bounce occurs when a recipient's mail server rejects delivery. We distinguish two types:
- Hard bounces — permanent failures (address does not exist, domain does not exist). The address is immediately added to your suppression list and will never be retried.
- Soft bounces — temporary failures (mailbox full, server temporarily unavailable). We retry with exponential back-off. If the same address soft-bounces repeatedly, it is treated as a hard bounce.
Accounts with sustained hard bounce rates above 5% are automatically rate-limited and flagged for manual review.
3. Complaint handling
A complaint is registered when a recipient clicks "Mark as spam" in their email client. Amazon SES forwards complaint notifications to us via feedback loops with major ISPs (Gmail, Outlook, Yahoo, and others).
- Every complaint address is immediately added to your suppression list and will never receive another email from your account.
- Complaint events are surfaced in your dashboard and available via webhook in real time.
- Accounts with complaint rates above 0.1% are rate-limited. Accounts above 0.5% are suspended pending review.
4. Suppression lists
Every account has a suppression list — a set of addresses that will never receive email from that account, regardless of what your application requests. Addresses are added automatically by hard bounces and complaints. You can also add addresses manually via the dashboard or API.
Attempting to send to a suppressed address returns an error and does not consume your sending quota.
5. Rate limits
All accounts are subject to sending rate limits, which vary by plan tier and sending history. Rate limits exist to:
- Protect our shared sending infrastructure from abuse
- Prevent a compromised API key from causing mass damage
- Give us time to review unusual spikes before they affect deliverability
If you have a legitimate high-volume use case, contact us before sending — we can adjust your limits proactively.
6. Manual review and account suspension
Our system flags accounts for manual review when it detects:
- Volume spikes more than 5× above a 7-day baseline
- Bounce or complaint rates above the thresholds described above
- Sending to domains with no prior engagement history
- API key usage from IP addresses or regions inconsistent with account history
When an account is flagged, we rate-limit it immediately and a human reviews it within one business day. We contact you by email before taking further action unless the violation is severe (phishing, purchased lists, malware), in which case suspension is immediate.
Suspended accounts are notified with a reason. Accounts suspended for spam or policy violations are not reinstated.
7. Reporting abuse
If you receive spam or malicious email that appears to originate from Transend infrastructure, please forward the full email headers to abuse@transend.email. We investigate all reports within one business day.