Postmark
Transactional email.
Verdict
Common use cases
- Diagnose why a customer didn't receive an email
- Pull weekly delivery stats for the exec dashboard
- Check bounce reasons before re-sending a campaign
- Audit open rates across transactional templates
- Surface spam complaints during a product launch
Integration
- Vendor
- Postmark
- Category
- communication
- Auth
- API_KEY
- Composio slug
postmark
Tools
Setup
Setup guide
- 11. In Switchy, open Settings → Integrations → Add Integration and select Postmark. 2. Log into your Postmark account, navigate to Servers, choose the server you want to query, then copy its Server API Token from the API Tokens tab. 3. Paste the token into Switchy's connection form and click Connect. 4. Switchy confirms the connection by fetching your server name and message count. 5. Open any Space, type '@Postmark show me today's bounce rate' and send — if the MCP replies with a percentage or table, the integration is live. 6. Remember the token is scoped to one server; to query a different server, add a second Postmark connection with its token.
What teammates see: by default, memories from Postmark are scoped to the Space (PROJECT visibility) - you can mark any memory PRIVATE or share it ORG-wide.
Works well with
Top models
Compatibility data appears once enough Spaces have used this MCP together with a given model.
How Switchy teams use it
Starter prompts
Bounce Report Today
@Postmark show me all bounced messages from the past 24 hours, grouped by bounce type and reason.Open in a Space →
Campaign Open Rate
@Postmark what's the open rate for messages tagged 'onboarding-series' sent in the last 7 days?Open in a Space →
Delivery Status Lookup
@Postmark check the delivery status of the most recent email sent to user@example.com.Open in a Space →
Weekly Send Volume
@Postmark how many emails did we send in the last 7 days? Break it down by day and stream.Open in a Space →
Spam Complaint Audit
@Postmark show me all spam complaints from the past 30 days, including recipient addresses and message subjects.Open in a Space →
Example outputs
Illustrative - representative of the model's voice and quality, not literal recordings.
@Postmark check the delivery status and open rate for emails sent in the last 24 hours to our trial users
In the last 24 hours, 847 emails were sent to trial users. Delivery rate: 99.2% (840 delivered, 7 bounced). Open rate: 34.1% (286 opens). Click rate: 8.9% (75 clicks). Average time to first open: 2.3 hours. The 7 bounces were all hard bounces due to invalid addresses. No spam complaints recorded. This data reflects the 'trial-onboarding' message stream.
Requires read access to message streams and statistics. Postmark tracks opens via pixel and clicks via link rewrites, so rates depend on recipient email client settings. Bounces are categorized automatically, but you'll need to handle list hygiene separately.
@Postmark send a transactional email to user@example.com with subject 'Your invoice is ready' using our invoice template and attach the PDF from our storage
Email queued for delivery. Message ID: f8a3c7e2-4b91-4d5e-9c8a-1e6f2d3a4b5c. Recipient: user@example.com. Template: 'invoice-ready-v2' applied with provided variables. PDF attachment (invoice-2847.pdf, 142 KB) included. Estimated delivery: within 60 seconds. You can track opens and clicks in the Postmark dashboard under this message ID.
Requires send permission and valid template ID. Postmark enforces a 10 MB total message size limit (body + attachments). If the template references dynamic content, ensure all required variables are passed or the send will fail with a validation error.
@Postmark analyze bounce patterns from the last 30 days and draft an email to our ops team explaining which domains are causing issues
Bounce analysis complete. Top 3 problematic domains: 1) oldcorp.net (23 hard bounces, all 'user unknown'), 2) startup.io (18 soft bounces, mostly 'mailbox full'), 3) enterprise.biz (12 blocks, flagged as spam by recipient server). Draft email: 'Team — our bounce rate spiked to 4.2% last month. oldcorp.net addresses are invalid (likely outdated list). startup.io users have full inboxes (retry in 48h). enterprise.biz is blocking us (check sender reputation, consider warming a new IP).' Recommend list validation before next campaign.
Combines Postmark's bounce webhook data with AI reasoning. Accuracy depends on how much historical data the MCP can access via API. Postmark categorizes bounces (hard, soft, spam complaint), but root-cause diagnosis requires context about your sending practices and list hygiene.
Use-case deep-dives
When Postmark MCP makes sense for delivery ops
A 6-person SaaS team ships password resets, invoice emails, and onboarding sequences through Postmark. The ops lead wants to debug a spike in bounce rates without leaving the AI workspace. The Postmark MCP lets you query delivery stats, pull bounce logs, and check suppression lists in the same thread where you're triaging customer tickets. This works if your email volume is under 10k/day and you're already using Postmark as your transactional provider. If you're on SendGrid or SES, this MCP won't help. If you need marketing campaign analytics (open rates, click maps), Postmark's API doesn't expose that depth anyway. The win is speed: you skip the Postmark dashboard login and get delivery context inline with your support workflow.
Postmark MCP for support teams debugging email delivery
A 3-person support team at a B2B app sees a pattern: new signups claim they never got the welcome email. The support rep pulls the Postmark MCP into a Switchy thread, searches by recipient email, and finds the message bounced due to a typo in the domain config. The MCP surfaces the bounce reason and timestamp without switching tools. This scenario assumes you're using Postmark for transactional sends and your support team already works in a shared AI workspace. If your email provider is Mailgun or Amazon SES, you'll need a different MCP. If your team is larger than 8 people, you probably have a dedicated ops dashboard and won't save time here. The call: use this MCP if your support flow is already in Switchy and you need delivery forensics on demand.
When Postmark MCP fits a dev team's release checklist
A 4-person dev team deploys a new feature that triggers a confirmation email. The lead engineer wants to verify the email actually sent before marking the deploy complete. They open a Switchy thread, call the Postmark MCP to check the last 10 sends, and confirm the template rendered correctly. This takes 30 seconds instead of opening the Postmark UI and filtering by timestamp. The trade-off: if your deploy checklist is already automated in CI/CD with Postmark webhooks, the MCP adds no value. If you're sending more than 50 emails per deploy (batch notifications, etc.), querying the API in a chat thread gets noisy. The fit is narrow: small teams doing manual smoke tests who want delivery confirmation without context-switching.
Frequently asked
What does the Postmark MCP do in Switchy?
The Postmark MCP connects your Switchy workspace to Postmark's transactional email service. Your AI agents can query delivery stats, check bounce logs, and pull template data without leaving the conversation. It's useful for support teams troubleshooting email delivery or marketing ops checking campaign performance alongside other tools.
Do I need admin access to connect Postmark?
You need a Postmark API key with read permissions at minimum. If your agents will trigger sends or update templates, you'll need a server token with write access. Postmark issues tokens per server, so coordinate with whoever manages your email infrastructure to get the right credential.
Can the Postmark MCP send emails directly?
That depends on which tools Postmark exposes through the MCP. Typically these integrations focus on read-only operations like fetching delivery stats or template content. If you need agents to send transactional emails, check the tool list once it's populated or use Postmark's API directly via a custom action.
Why use this instead of Postmark's dashboard or API?
Use the MCP when you want email data in the same thread as Slack messages, GitHub issues, or analytics queries. The dashboard is faster for one-off checks; the API is better for programmatic workflows. The MCP shines when your team asks questions like 'why didn't this user get our onboarding email' and the agent pulls Postmark logs alongside user records.
Does connecting Postmark count against my Switchy plan limits?
Connecting the MCP itself doesn't count as a seat or integration slot. API calls your agents make to Postmark do count toward your workspace's monthly action quota, so heavy usage of delivery lookups or template fetches will burn through that budget faster than lighter integrations.