> For the complete documentation index, see [llms.txt](https://doc.batch.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://doc.batch.com/guides-and-best-practices/email-deliverability/email-authentication-and-sending-structure/sending-subdomain-setup-and-troubleshooting/troubleshooting-email-authentication-issues.md).
# Troubleshooting Email Authentication Issues
You will find here all the information you need to troubleshoot issues with SPF, DKIM and DMARC.
A variety of tools exist to help you check if your emails are correctly authenticated.
## Send a Test Email
Send a test email from your subdomain and then **check the email headers**.
Most mailbox providers will indicate whether your email is correctly authenticated. For example, in Gmail, open the email, click the **three dots** in the top right corner, and select "**Show Original.**"
## Use a DNS Debug Tool
You can also use dedicated DNS debug tools like [EmailStruff's DNS tool](https://emailstuff.org/dns).
#### → SPF:
* **Strict alignment**: Type your subdomain name in the TXT field of the tool (`subdomain.domain.com`)
* **Relaxed** **alignment**: Type your bounce subdomain name in the TXT field of the tool (`bounce.subdomain.domain.com`)
#### → DKIM
Type the selector + your subdomain name in the TXT field of the tool (`scphxxxx._domainkey.subdomain.domain.fr`).
#### → DMARC
Type `_dmarc.subdomain.domain.com` in the TXT field of the tool to check your DMARC record.
## Dig Command
Alternatively, you can use the `dig` command following the same logic:
```
dig TXT subdomain.domain.com
```
## Common Issues with Strict Alignment
When operating in strict alignment mode, the presence of **TXT entries** within the same domain **often disrupts email authentication**.
The most frequent cause is a **Google Postmaster Tools** verification code being incorrectly placed at the subdomain level. Ensure that you only verify your root domain with Google Postmaster Tools.
Subsequent subdomains do not require individual verification to be added to the tool's monitoring.
---
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