[RF DOCS] Action Mailbox Guides

[bhumi1102]

Overview

Action Mailbox is a pretty useful / interesting sub-framework of Rails, that more apps probably could benefit from. It does have a number of moving parts so I focused on explaining the flow of how things work. I did a lot of 'in-app testing' of the docs by implementing its features in a rails app and exploring what's missing in the docs.

New sections

Here are the new things I added, in addition to clarifying the existing text.

• Processing Incoming Email - more of a step by step of the flow
• Mail object and it's fields
• List of Inbound Email 'status' values
• ActiveJobs that are part of Action Mailbox - Routing and Incineration

Testing

In addition to testing the Action Mailbox features in-app, I also ran guides:generate and guides:validate locally and got the All checked guides validate OK! output. I perused the generated html locally as well.

Follow-on Task

Moving the Ingress Configuration: the Ingress configuration section reads more like a reference/appendix to me. I think it'd make sense to move that to the end of the doc. With a smaller section with the common steps in its current place (create secure pwd, update config.action_mailbox.ingress) and then point to the bottom of the docs for details on the specific. I did not do that yet as I wanted to focus on adding the new sections first instead of moving things around.

I did test the instructions for one 'real' ingress Postmark (locally with ngrok). I did not test all the other ones (as Carlos mentioned it's be too much).

[Ridhwana]

This reads really clear and concise 😊 . I left a few non-blocking suggestions.

[carlosantoniodasilva]

This is looking great! I just had a few bits of feedback, mostly links I think we can add to make navigation within the doc easier, and some small suggestions here and there. Let me know if you have any questions.

[bhumi1102]

Great updates! I had one thought about a possible small addition to the routing section that may be worth mentioning, and a couple other minor bits to consider, but otherwise this LGTM. Thanks @bhumi1102!

Awesome. Thank you for the great thorough review @carlosantoniodasilva! Looking forward to merging this to rails/rails after our 'community feedback window'.