Security audit
Security checks for vulnerabilities and agentic risk
This is a Mailtrap email-sending reference skill with live-send examples, but its behavior is disclosed, purpose-aligned, and not executable by itself.
Install only if you want Codex help wiring Mailtrap live email. Review any generated send command before running it, use sandbox or verified test recipients first, and keep the Mailtrap API token scoped and stored in environment variables or a secrets manager.
The skill gives detailed instructions for live transactional and promotional email sending but does not prominently warn that the examples can send real messages to actual recipients. In an AI-assisted workflow, this increases the chance of accidental delivery, spam, or unintended outreach if placeholder addresses or copied examples are used without sandbox/test guidance.
Skill attempts to fill the context window with filler content, displacing legitimate instructions and safety constraints. This can degrade agent performance or bypass safety boundaries.
## Choosing how to send
| Approach | Use when |
| --------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Transactional, single message** | Email **generated by your app** (password resets, receipts, notifications, alerts). One logical message per `POST https://send.api.mailtrap.io/api/send` |
| **Bulk** | **Promotional** email **to contacts that you manage on your side** and send at volume through Mailtrap. Not the same as "batch": bulk is the **stream**, not the batch endpoint. |
Large whitespace padding was detected (a block of blank lines or a long run of spaces). This can push injected instructions below or to the right of the visible area so a human reviewer never sees them while the agent still reads them. Manual review of the hidden content is recommended.
## Choosing how to send
| Approach | Use when |
| --------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Transactional, single message** | Email **generated by your app** (password resets, receipts, notifications, alerts). One logical message per `POST https://send.api.mailtrap.io/api/send` |
| **Bulk** | **Promotional** email **to contacts that you manage on your side** and send at volume through Mailtrap. Not the same as "batch": bulk is the **stream**, not the batch endpoint. |
Large whitespace padding was detected (a block of blank lines or a long run of spaces). This can push injected instructions below or to the right of the visible area so a human reviewer never sees them while the agent still reads them. Manual review of the hidden content is recommended.
| Approach | Use when |
| --------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Transactional, single message** | Email **generated by your app** (password resets, receipts, notifications, alerts). One logical message per `POST https://send.api.mailtrap.io/api/send` |
| **Bulk** | **Promotional** email **to contacts that you manage on your side** and send at volume through Mailtrap. Not the same as "batch": bulk is the **stream**, not the batch endpoint. |
| **Batch** | You have **multiple different messages** to hand off **at the same time** (up to 500 per request). Cuts HTTP overhead; can be applied to both transactional and bulk |
| **Campaigns** | **Promotional** email to recipients stored as **Mailtrap contacts**, using Mailtrap **Campaigns** (audiences, scheduling, reporting in the product). **Recommended** to avoid implementing conta
...[truncated 25 chars]
Large whitespace padding was detected (a block of blank lines or a long run of spaces). This can push injected instructions below or to the right of the visible area so a human reviewer never sees them while the agent still reads them. Manual review of the hidden content is recommended.
| Approach | Use when |
| --------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Transactional, single message** | Email **generated by your app** (password resets, receipts, notifications, alerts). One logical message per `POST https://send.api.mailtrap.io/api/send` |
| **Bulk** | **Promotional** email **to contacts that you manage on your side** and send at volume through Mailtrap. Not the same as "batch": bulk is the **stream**, not the batch endpoint. |
| **Batch** | You have **multiple different messages** to hand off **at the same time** (up to 500 per request). Cuts HTTP overhead; can be applied to both transactional and bulk |
| **Campaigns** | **Promotional** email to recipients stored as **Mailtrap contacts**, using Mailtrap **Campaigns** (audiences, scheduling, reporting in the product). **Recommended** to avoid implementing conta
...[truncated 25 chars]
Large whitespace padding was detected (a block of blank lines or a long run of spaces). This can push injected instructions below or to the right of the visible area so a human reviewer never sees them while the agent still reads them. Manual review of the hidden content is recommended.
| --------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Transactional, single message** | Email **generated by your app** (password resets, receipts, notifications, alerts). One logical message per `POST https://send.api.mailtrap.io/api/send` |
| **Bulk** | **Promotional** email **to contacts that you manage on your side** and send at volume through Mailtrap. Not the same as "batch": bulk is the **stream**, not the batch endpoint. |
| **Batch** | You have **multiple different messages** to hand off **at the same time** (up to 500 per request). Cuts HTTP overhead; can be applied to both transactional and bulk |
| **Campaigns** | **Promotional** email to recipients stored as **Mailtrap contacts**, using Mailtrap **Campaigns** (audiences, scheduling, reporting in the product). **Recommended** to avoid implementing contact management and email sending logic; **requires UI setup** before sends flow—this skill does not replace that workflow. |
**Before generating SDK code:** read the README of the relevant SDK repository linked in the **SDKs** section below for current method signatures, constructor options, and examples. Do not rely on memory.
The curl examples perform real external transmission to Mailtrap live sending endpoints using a bearer token, which could cause actual email delivery if copied into a terminal with valid credentials. In a skill meant for operational use, this is not inherently malicious, but it is risky because it enables immediate outbound communication and possible data disclosure to third-party recipients.
Transactional send (send.api.mailtrap.io):
curl -X POST https://send.api.mailtrap.io/api/send \
-H "Authorization: Bearer $MAILTRAP_API_TOKEN" \
-H "Content-Type: application/json" \
-d '{
Large whitespace padding was detected (a block of blank lines or a long run of spaces). This can push injected instructions below or to the right of the visible area so a human reviewer never sees them while the agent still reads them. Manual review of the hidden content is recommended.
## Common mistakes
| Mistake | Fix |
| -------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------- |
| Confusing **batch** with **bulk** | **Batch** = many messages in one `/api/batch` request. **Bulk** = promotional stream/host and token |
| Promotional API mail on transactional host | Use bulk base URL and bulk token for promotional content you generate in code |
Large whitespace padding was detected (a block of blank lines or a long run of spaces). This can push injected instructions below or to the right of the visible area so a human reviewer never sees them while the agent still reads them. Manual review of the hidden content is recommended.
| -------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------- |
| Confusing **batch** with **bulk** | **Batch** = many messages in one `/api/batch` request. **Bulk** = promotional stream/host and token |
| Promotional API mail on transactional host | Use bulk base URL and bulk token for promotional content you generate in code |
| Bulk traffic on `send.api.mailtrap.io` | Promotional/bulk stream uses `bulk.api.mailtrap.io` |
| Using sandbox SMTP host for live sending | Live sending uses `live.smtp.mailtrap.io` or `bulk.smtp.mailtrap.io` |
| SMTP username is an email address | Username is `api`; password is the API token |
| Sending before domain is verified | Complete **Sending Domains** setup and compliance (see `setting-up-sending-domain`) |
Large whitespace padding was detected (a block of blank lines or a long run of spaces). This can push injected instructions below or to the right of the visible area so a human reviewer never sees them while the agent still reads them. Manual review of the hidden content is recommended.
| Promotional API mail on transactional host | Use bulk base URL and bulk token for promotional content you generate in code |
| Bulk traffic on `send.api.mailtrap.io` | Promotional/bulk stream uses `bulk.api.mailtrap.io` |
| Using sandbox SMTP host for live sending | Live sending uses `live.smtp.mailtrap.io` or `bulk.smtp.mailtrap.io` |
| SMTP username is an email address | Username is `api`; password is the API token |
| Sending before domain is verified | Complete **Sending Domains** setup and compliance (see `setting-up-sending-domain`) |
| Guessing SDK API from memory | Read the SDK README and OpenAPI-linked examples; do not invent constructors or method names |
| Choosing **SMTP first** for a greenfield app | Prefer **platform integration** if one exists, then **SDK**, then **HTTP API**; SMTP only when necessary (see **How to integrate**) |
No suspicious patterns detected.