docs: document Mailpit plus-address auto-tagging and how to disable it (#8222) [skip ci]

[maks-oleksyuk]

Adds documentation explaining Mailpit's auto-tagging behavior and provides instructions on how to disable it using the MP_TAGS_DISABLE=plus-addresses environment variable.

Includes both global and per-project configuration examples.

Manual Testing Instructions

• Open the Mailpit documentation section in DDEV docs https://ddev--8222.org.readthedocs.build/en/8222/users/usage/developer-tools/#email-capture-and-review-mailpit
• Verify that the new note about auto-tagging is present and correctly formatted.
• Optionally:
  • Send an email to an address like user+1@example.com
  • Confirm that a tag is created
  • Apply the environment variable and confirm that tagging is disabled

Automated Testing Overview

No automated tests were added, as this PR only updates documentation.

Release/Deployment Notes

No impact on runtime behavior. Documentation-only change.

[github-actions]

Download the artifacts for this pull request:

• ddev-windows-arm64-installer.zip
• ddev-windows-arm64.zip
• ddev-windows-amd64-installer.zip
• ddev-windows-amd64.zip
• ddev-linux-amd64.zip
• ddev-linux-arm64.zip
• ddev-macos-arm64.zip
• ddev-macos-amd64.zip
• all-ddev-executables.zip

See Testing a PR.

[rfay]

Hi @maks-oleksyuk - Can you say more about why this is important to you, and why change DDEV itself instead if just doing

web_environment:
   - MP_TAGS_DISABLE=plus-addresses

in your affected project?

[maks-oleksyuk]

@rfay, during testing, it looks like this, and it's a little confusing what these tags are and where they come from. I turned it off for me using the env variable as you wrote, but I think this fix will also help prevent cases like mine.

[rfay]

But, since it's changing the default behavior, it might also adversely affect somebody else.

[rfay]

Super interesting!

[maks-oleksyuk]

Well, I don't think it will have much of an impact on anyone. On the contrary, at first I didn't understand where these tags came from and what I was doing wrong (since I was testing notifications)

And this is very non-obvious behavior when creating tags, and it doesn't affect the content of the letter itself or anything else

[penyaskito]

Agree with @rfay that changing the default settings of Mailpit might be even more confusing for other users.
But maybe this could be a very simple ddev add-on instead?

[stasadev]

BTW, it can be set globally in the global user's config for all projects ($HOME/.ddev/global_config.yaml), if those tags are distracting:

ddev config global --web-environment-add=MP_TAGS_DISABLE=plus-addresses

I'm not sure about disabling this feature for everyone, since some people may benefit from it.

[stasadev]

@maks-oleksyuk,

What do you think about turning this PR into a docs PR?

You could update https://docs.ddev.com/en/stable/users/usage/developer-tools/#email-capture-and-review-mailpit and add the example I gave above about how to control this behavior globally.

See https://github.com/ddev/ddev/blob/main/docs/content/users/usage/developer-tools.md?plain=1#L126

[maks-oleksyuk]

@stasadev, okay, that's a good idea. I'll update it when I get a chance, but for now I'll mark it as a draft
Thanks for the advice on the global configuration; it's really helpful for me

[rfay]

Thanks for the contribution. A little note for the docs in a future PR will be welcome. Closing this for now.

[maks-oleksyuk]

@rfay, why was it closed? I added a commit that includes a note in the documentation—did I do something wrong?

[stasadev]

@maks-oleksyuk, could you update the title and the first post to follow our template.

Right now, they don't reflect what was done here.

[rfay]

I expected you to open a new PR with appropriate information, since the target changed.

[stasadev]

Looks good to me.

Review at https://ddev--8222.org.readthedocs.build/en/8222/users/usage/developer-tools/#email-capture-and-review-mailpit

[rfay]

Works for me, thanks.