Sending a Patch to the Linux Kernel from an .mbox File (and Solving SMTP Issues)

Recently, I needed to send a patch to the Linux kernel for the IIO subsystem. The patch came as an .mbox file, and the task involved several steps: applying the patch, generating a clean commit, and sending it via email using git send-email.

Along the way, I encountered a common but frustrating problem: SMTP misconfiguration.

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The Context: Receiving the .mbox Patch

The patch did not arrive as a traditional .diff or .patch file. Instead, it came in .mbox format — a format used to store full emails, often used for mailing list workflows.

After attempting to apply the original patch, I encountered this error:

error: corrupt patch at line 76
Patch failed at 0001 iio: light : veml6030: Remove code duplication

David Tadokoro kindly sent me a correct .mbox version of the patch. Applying it was straightforward:

git am patch.mbox

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SMTP Problem: Sending from my IME-USP Email Failed

Initially, I tried sending the patch from my institutional email gabriellimamoraes@ime.usp.br.

However, I soon realized that I didn’t have SMTP properly configured for this account, and my attempts to send patches with git send-email were failing silently or being rejected by the mail server.

My .gitconfig had these settings at first:

[sendemail]
    smtpServer = smtp.ime.usp.br
    smtpServerPort = 587
    smtpEncryption = tls
    smtpUser = gabriellimamoraes@ime.usp.br
    smtpPass = <password>

But sending did not work.

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Solution: Switching to Gmail SMTP

To quickly resolve the issue, I switched to my personal Gmail account.

I updated my .gitconfig:

[sendemail]
    smtpServer = smtp.gmail.com
    smtpServerPort = 587
    smtpEncryption = tls
    smtpUser = gabriellimamoraes@gmail.com
    smtpPass = <Gmail App Password>

Then, I tested with:

git send-email --smtp-debug=1 --to="linux-iio@vger.kernel.org" --cc="gabriellimamoraes@ime.usp.br" HEAD~1

The log showed a 250 OK response from the SMTP server, indicating successful delivery.

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Correct Mailing List Address: linux-iio@vger.kernel.org

Another issue: initially I was trying to send the patch to iio@lists.linux.dev, which returned this error:

550 5.1.1 : Recipient address rejected: User unknown in virtual alias table

After checking the official vger.kernel.org mailing lists, I confirmed that the correct address for the IIO subsystem is:

linux-iio@vger.kernel.org

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Final Send Command

git send-email --to="linux-iio@vger.kernel.org" --cc="gabriellimamoraes@ime.usp.br" HEAD~1

Final result:

• Email successfully sent
• I received a copy in my inbox (Cc)
• The patch appeared on lore.kernel.org

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Lessons Learned

• Always double-check the mailing list address on official pages like vger.kernel.org
• Configure SMTP with a reliable provider: Gmail worked well for me
• Use --smtp-debug=1 for troubleshooting
• Cc yourself if you want a copy of your patch submission
• Confirm on lore.kernel.org to ensure your patch was published

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Contributing to the Linux kernel can be challenging, but it’s a rewarding learning experience

Link to my patch on lore.kernel.org

You can view the final result of my patch submission here:

👉 https://lore.kernel.org/all/20250623201539.16148-1-gabriellimamoraes@gmail.com/