Use email as an inbound channel
Your customers send documents, enquiries or orders to an address your software recognises.
Email inbound as an embedded service for software
Receive email in your software without building the service
You assign the email addresses; CatchMail handles the inbound service. It evaluates the mail server’s sender authentication results, applies your rules, stores complete messages and attachments, and delivers them to your system over HTTP. We have used CatchMail in production for document delivery in GetMyInvoices since September 2025. Since summer 2026, it has also served a ticketing system that creates a case from every incoming email. Both are our own products.
The work involved in building your own service often becomes clear only in production. A genuine email passes DKIM but fails SPF. Attachments in a reply-all chain prevent delivery. A target system returns 502, and nobody notices the message did not arrive. We have encountered these cases ourselves and built the solutions into CatchMail.
CatchMail · the path of a message
Received at an address you assign
Accepted
SPF and DKIM evaluated separately
SPF ✗ · DKIM ✓
Rules apply before your process
passed
MIME original and attachments stored
Checksum
Delivery to your endpoint
502
Retry at ten-second intervals
Delivered
- In production since September 2025
- Two connected systems
- Weekly release cycle
- Daily automated end-to-end tests
When CatchMail fits your product
Your product needs to receive email without your team having to build and run the inbound service. That is what CatchMail is for.
Avoid building complex filtering yourself
Blocklists, allowlists, spam scoring and separate SPF and DKIM checks take more than a single development ticket. CatchMail covers these tasks.
Keep the complete original
Store the complete MIME original, every header and every attachment in a traceable way, not just the message text.
Handle brief outages during delivery
When your system is temporarily unavailable, you need retries, status tracking and a way to restart delivery manually.
What CatchMail handles for your email inbound
Receive email at your own inbound addresses
You define the addresses; we receive the email. Before processing, every incoming message is checked against our mail provider’s signature. Without a valid signature, CatchMail returns 403 and does not process the message. You can enable an additional recipient-address check.
CatchMail does not retrieve third-party mailboxes. Use MailTacle when users need to connect existing Gmail, Microsoft 365 or IMAP accounts.
Filter messages using your rules
Allow, exclusion and spam rules determine which messages reach your process. They check the sender, recipient, subject, headers and message body. The presence of an attachment can also be a condition. SPF and DKIM are evaluated separately, not combined into one verdict: legitimate business email often passes only one of the two checks.
CatchMail makes the technical decision about forwarding. Your application handles the business meaning of the content.
Keep complete, traceable message records
We store the complete MIME original and record all headers separately as metadata. The original and its attachments share a dedicated location in object storage, derived from a checksum. Every message has a complete audit trail and can be filtered by message ID. By default, it moves to the archive after 45 days and can be retrieved from there. The EML file is deleted after 90 days, and the record is physically removed after 365 days. We agree these periods with you and adjust them as needed.
How to integrate CatchMail into your application
Define inbound addresses and target system
Define which addresses receive email and which URL we deliver to. The destination is a freely configurable HTTPS address. We agree the payload, authentication and status response for your integration, as we have done for our two existing connections.
Set up the rule set
We configure blocklists, allowlists and spam thresholds for your inbound service. The allowlist remains an emergency route. If messages routinely need to bypass checks, the rules generally need adjusting rather than adding more exceptions.
Receive and store messages automatically
CatchMail receives each message, checks it, stores it and schedules delivery. From this point, reception and storage run automatically.
Agree how delivery retries work
Delivery uses HTTP. The default is up to twelve attempts at ten-second intervals, with both values adjustable. We define how each connection handles individual response codes. In our two existing integrations, for example, 502 triggers another attempt while 4xx does not: waiting does not fix a client error. Your team knows exactly which delivery behaviour to expect.
Spot failures and restart deliveries
The dashboard shows Received, Pushed, Push failed and Spam. You can inspect error details, restart failed deliveries individually or in bulk, and save filters as views. If mail volume drops, Slack and email alerts let you respond before customers report the problem. We introduced this monitoring after such an incident in our own production environment.
For technology companies with email-based product features
Software vendors, SaaS and platform operators
You develop software, a SaaS offering or a platform and want to add email as an inbound channel. CatchMail is built for your product, engineering and integration teams.
Internal product teams in larger organisations
You need a shared email inbound for several applications. This is how we use CatchMail ourselves: one instance serves multiple tenants, with messages assigned through a recipient lookup.
The operations interface is available in German and English, with a role model and a documented permissions matrix. During setup, we agree whether your team gets its own access or we take care of operations.
What we handle and what stays with you
| CatchMail handles | Your application handles |
|---|---|
| Receiving email at your addresses and checking senders | Providing the product interface for your users |
| Applying blocklist, allowlist, spam and mail authentication | Assessing and using content in context |
| Storing MIME original, headers and attachments in an audit-proof way | Processing documents or data further |
| Delivering to your endpoint, including retries | Steering the subsequent business process |
| Making status, errors and volume alerts visible | Triggering feedback to your users |
CatchMail does not connect your users’ existing mailboxes; MailTacle handles that. The Email Classifier decides whether a message contains an invoice. Extronaut extracts individual fields from documents. All three can be placed behind CatchMail.
Frequently asked questions about CatchMail
CatchMail receives email at your inbound addresses, checks signatures and applies rule-based filters. It stores originals and attachments in an audit-proof way and delivers them to your endpoint with defined retries. Your operations team gets a status overview and alerts.
No. CatchMail processes email sent to your inbound addresses. MailTacle provides access to your users’ existing mailboxes.
Any reachable HTTPS endpoint that accepts POST requests. The target URL is freely configurable. The main integration step is agreeing the payload, authentication and status response for your system.
The default is twelve delivery attempts at ten-second intervals. We define how each connection handles individual response codes. You can see the status of every message and restart failed deliveries individually or in bulk. The message is retained throughout this process.
By default, a message is archived after 45 days and can be retrieved from there. The EML file in object storage is deleted after 90 days, and the record is physically removed after 365 days. We can agree shorter or longer periods.
CatchMail has been in production since September 2025 and now serves two systems. Operations include weekly releases, daily automated end-to-end tests, container scans in the build, monitoring and alerting. The first system’s customer rollout ran in controlled waves of 50 accounts. The component has no external customers yet. You would be its first external customer.
Let's plan email inbound for your product
In our first conversation, we discuss your inbound addresses, required rules, delivery endpoint and how your operations team will see errors. You then have a basis for comparing the integration with building your own service.