--- title: Receive and process inbound email with Ruby on Rails slug: receive-and-process-inbound-email-with-ruby-on-rails published_at: 2021-09-06 13:00:17 +0000 updated_at: 2026-03-04 20:13:57 +0000 summary: description: In this episode you'll learn the pieces for setting up inbound email processing so you can receive emails with your Ruby on Rails applications. We'll setup action mailbox and route an inbound email that is meant to be a reply to a comment. #rails #rubyonrails tags: [cjav_dev, web development tutorials, web development for beginners, vim, ruby, rails, javascript, action mailbox] views: 2561 author: CJ Avilla url: https://www.cjav.dev/videos/receive-and-process-inbound-email-with-ruby-on-rails youtube_url: https://www.youtube.com/watch?v=jOfAV2QWNOw youtube_id: jOfAV2QWNOw embed_url: https://www.youtube.com/embed/jOfAV2QWNOw thumbnail_url: https://i.ytimg.com/vi/jOfAV2QWNOw/hqdefault.jpg type: video --- # Receive and process inbound email with Ruby on Rails *Published: September 06, 2021* *Views: 2561* ## Watch [Watch on YouTube](https://www.youtube.com/watch?v=jOfAV2QWNOw) [![Receive and process inbound email with Ruby on Rails](https://i.ytimg.com/vi/jOfAV2QWNOw/hqdefault.jpg)](https://www.youtube.com/watch?v=jOfAV2QWNOw) ## Description In this episode you'll learn the pieces for setting up inbound email processing so you can receive emails with your Ruby on Rails applications. We'll setup action mailbox and route an inbound email that is meant to be a reply to a comment. #rails #rubyonrails ## Transcript hey what's up welcome back we're playing around with email again today we're going to try to build out a receiver for email address using action mailbox it's a pretty new feature of rails and in the last episode we built out a tool where we could send emails from a comment dash and then the id of the comment and in this episode we're going to do the other side of that where we're going to resp or we're going to like simulate replying to those comment email notifications and use the content of the response email as the you know the body that might be added directly to the reply here so right now what we've got going on is if we reply to a comment we can say like you know hey this is my reply and if we click submit that sends an email this is what the email looks like we're using letter opener to sort of simulate that email actually sending and we can see the um the id of the comment that was just added and now what we want to do is make it so that we can reply to this email and have that reply show up on um on the as a reply to that thread so here it would just show down here like hey this is my reply and then under that it would be our response from the email that we received so uh action mailbox super cool pretty new um pretty new feature for rails this is like part of the thing that they use to build out hay um and so yeah let's get started we're going to say rails action mailbox install this is going to install actually a couple different things so first it's going to install a a new action mailbox class for us in this new directory mailboxes it's also going to copy some migrations over for the action mailbox stuff but action mailbox depends on active storage so it's also giving us some active storage migrations so let's just run those we'll say rails db migrate cool so now that we have migrated our database we can generate a new mailbox we can say rails g mailbox comments okay so the way that this works is the each mailbox is sort of like its own controller for handling certain types of messages so we can sort of think of this as like a comments controller for content or posts that are received through the through the email system so let's let's open this up and take a look at what we've got so it is a class that inherits from application mailbox so let's look at application mailbox application mailbox and application mailbox here has a comment about routing so the application mailbox routing feature is sort of like routes so we have routes.rb and those routes end up you know directing reque inbound http requests from the browser to certain controllers well application mailbox is responsible for routing emails that are coming in to specific mailboxes so what we do here is we route based on the in the the from email address space or the i'm sorry the two email address so in our case we've got this email address that's coming in comment dash 34 at reply.example.com um and so what we want to do is we want to write a regular expression for uh for checking to see if the inbound email address matches this and so instead of 34 here i'm going to use a digit so i'm just going to say as long as we receive something with comment dash d plus then we want to route it to our comments mailbox so that this comments key here matches the name of our mailbox over here okay cool now inside of process we have access to this thing called mail which is has like a two it has a from it has a decoded body it has a bunch of other stuff this is actually an object from the mail gem so there's a bunch of stuff about reading email address here email addresses here and so what we want to do is we want to well okay so yeah so let's talk about all the different pieces that we need so in order to make a comment we need to know we need to know the user we need to know the original comment that this new email address is in reply to and we need to know what else we need to know i think that's it so let's find let's find the user so the user we should be able to look up based on the from address that's on the mail object so this should be like at user is equal to user.find by email and that's going to be mail.from and we also need to know the comment and so we're going to say like at comment or equals comment dot find comment id and we need to look up the comment or we need to like figure out the comment id based on this sort of regular expression here and when we're receiving this email message we are going to be one of the email addresses in the to field right so like um i think mail dot 2 um this just shows a string [Music] so yeah so here so when we're receiving the email the two like the two address could technically be multiple different addresses i think so what we want to see here is okay so this one is to a specific email address um all right so let's let's just go so mail.2.match actually let's let's add a uh let's add a breakpoint in here and we also want to like just kill the mailbox processing if either the comment or the user doesn't exist but before we do that um i'm going to just drop in by bug here so that we can take a look at the processes that are inbound i think we might need to restart the rail server and then there is a special route that you can go to so on the action mailbox page here if you go down to number six working with action mailbox and development it gives you this route that you can copy and it's added to your routes file for you and there's a bunch of tools in here for messing around with inbound emails so we can say new inbound email by form and this allows us to just create an email in this editor and that will sort of deliver it as if we had received the email address so or received the email so here let's say this is coming from wave cgab.dev and it's going to go to comment 33 at example.com the the 2 doesn't really matter or like the the actual domain doesn't really matter right now but what we care about is this format here so like if we in fact like let's just look real quick at like la if we just send it with blah right then uh it's not going to match any of our any of our routing so blah doesn't match comment dash some digit so when we refresh this it's going to go from pending to failed or bounced or whatever because it doesn't actually have a route so now this shows us bounced so if we go back to all inbound email we create a new email and we say that it's coming from that and it's going to comment let's do 33 and we're going to say this is our test body test test email body okay and then we say deliver inbound email now it says processing and this should technically hit our match our our routing here and then enter our process and break on by bug and it has so here in the server log i can start messing around so if i say mail.2 okay so mail.2 gives me an array of strings mail.from okay that's also an array if i say mail. so what we want to do is try to figure out how to pull out 33 here so mail.2.find something that matches m.match like comment dash something like that so that should give us back just the string for the matching email address so that's going to be our to address and then we'll want to use that to somehow pull out the actual comment id so um comment id is equal to so uh we want to use um some sort of regular expression to pull this out so i think if we do like two dot match and then we say comment instead of using just like a normal regular expression here i'm going to use a capture group so we're going to use parentheses to do our capture group and we can make it case insensitive and inside of our capture group i'm going to do a question mark with the with these angle brackets and name this comment id and then i'm going to add my regular expression inside of the capture group so what this should give us back is a match data object that has comment id as one of the fields here and then i can use that as like comment id to pull out the actual number there so um this is sort of like messing around with if you're curious about regular expressions in general i would recommend checking out rubular um there's a bunch of stuff about regular expressions on here they're not super fun i would say generally avoid them but for when you're working with emails you will actually use regular expressions a surprising amount and so um okay so we're grabbing out the comment id and then we want to use that to actually look up our comment so if we run this again so we can actually go back to our rails server we'll continue so that it finishes that request we'll refresh the page we see that it was delivered we can say route again so that we can break in our mailbox by bug debugger again and now we can say user we can see the user we can see comment and we see the comment and that's great so now we can do maybe we want to do i guess what we want to do here is say like if or like return if user.nil return if comment.nil and then we want to like actually create the comment so recall that um in the comments controller here when we create the comment we are expecting the content and the parent id and so what we want to do here is basically say like comment is equal to user.comments.new and we want to pass in the content which is going to be mail.decoded so if we go back over to this mail gem here there's a bunch of different methods that you can use but one is decoded that's the content like the body content of the email and then we also want to say parent id and that's going to match our parent comment id so this comment here is actually the parent comment so maybe we rename this to parent um here we say parent.id um or even just like this okay so then we have um built a comment if comment.save um i guess maybe we can just use create bang here so that it will raise an exception i don't know there's i think there's tools for dealing with um if you're if you if you fail to save or whatever but let's just play around with this and see if this works for us all right so we're going to go back over to our rails conductor we see that it was pending oh we got to continue our rails log there okay so delivered so let's say route again pending and it crashed okay so what's going on here [Music] um [Music] uh post must exist validation failed post must exist um huh oh we have to pass in the post id too comment oh that's right that's totally right okay so i forgot about that so we have to pass in the post which is parent.post all right let's route this thing again and see what we get hey this looks positive okay okay delivered that's great all right now let's go take a look here at uh i guess how do we figure out which post this is for um okay so um post id okay maybe it was post 11 let's just see post 11. posts slash uh 11 and test email body amazing okay so let's let's actually this is this is getting a little messy and hard to find so let's actually make a new post email testing testing create a post um and if we log out and we log back in as another user and that user goes to posts oh no what was the id post 12. um okay so this is the new post right we're logged in as a different user and if we say this should email the author of the post and we say submit okay great that emailed the author of the post and we got the this email from comment number 36 and um so that's what we're going to use to reply to so we actually want to go get what is it i guess it's rails action mailbox inbound email so we're going to make a new email from comment 36 or to comment 36 from some other address so who are we logged in as we're logged in as we yeah so this should come from cjville gmail.com and this is going to be in reply to the author of the comment so this so this should show as a comment that is in reply to the first comment on that post and i don't know whatever whatever subject we're actually using the subject right now so that's okay deliver inbound email processing delivered we head back over here refresh the page wow look at that this should reply as a comment to the first post so at this point the next steps are to actually deploy this out to out to production and connect it to a real email service provider and um right now action mailbox has support for several so this is like all the different email providers that you could use i've in the most recent email episode that we showed how to set this up for sending in production we use send grid so i think maybe uh in a future episode we will go through the process for actually configuring your action mailbox to deliver email inbound from sendgrid thanks so much for watching really appreciate your time and attention and hopefully this was uh hopefully this was interesting and a little bit useful and yeah we'll look forward to to chatting soon [Music] --- [Back to all videos](https://www.cjav.dev/videos) --- ## Hey Agent, thanks for visiting! 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