In this video I'm showing how to programmatically send email in Java using the Gmail API, how to configure your Gmail account, and how to create and use credentials. For more information see: blog.sebastian...
Do you really not use any more dependencies? I had to go to maven repository and download another .jar file for every other Alt+Enter you made. Do you maybe have an overarching library which has all of those included?
My previous comment disappeared. The problem is that Google gives you token/credentials that is valid only for 7 days when application is in "test" status. And making an application public is another story.
Very good video, is there something that is not clear to me when I send an email using an API, it is not done through an SMTP server? How would it be sent in that case?
Yes, sure. If you use Quarkus/some framework, you can also combine a templating engine such as Qute to send HTML. For the sender it makes little difference, it just depends how the email program displays the HTML then.
Hello, as you said in the video you store the credentials in a directory "tokens". In this directory there is a crypted file which stores the credentials. Is there another way to store credentials or parse credentials to the application. I already have an access token and a refresh token that I would like to use.
Yes, this definitely works. The only confusing bit is that there are multiple (competing) libs from Google side. If you use my example project, search for a `GoogleCredential` class, which unfortunately is deprecated, but if that's not an issue for you then this works. The deprecation notice also points you to a google-auth-library-java project, which also implements this, but I don't have any example code for that right now...
@@SebastianDaschnerIT Thanks a lot. GoogleCredential works for me. val depricatedGoogleCredential = GoogleCredential.Builder() .setTransport(httpTransport) .setJsonFactory(jsonFactory) .setClientSecrets(apiKeys["GOOGLE_CLIENT_ID"], apiKeys["GOOGLE_CLIENT_SECRET"]) .build() .setAccessToken(apiKeys["GOOGLE_ACCESS_TOKEN"]) .setRefreshToken(apiKeys["GOOGLE_REFRESH_TOKEN"])
Could you make another video with an example of how to store the credential file in a database (preferably mongoDB) and how to use refreshToken to renew accesToken?
The JSON file is just an example. You would not deploy an application like this. You would use environment variables or GCLI when deploying an application.
How to make it work for production? I get problem with Receiver. In google cloud project i have set redirect uri as app url, but local receiver has host as localhost, and i get error missmatch. But, if i match host same as redirect uri, i get error on backend that host cannot be set. So i dont know what to do.
You can change the localhost receiver url in the code (IIRC that was documented somewhere) to make that work there (but then, also the extra port or URL has to be publicly reachable...), or you copy your credentials file to your production env (I've done that before), or you have access to the google admin console (I think you need a GSuite account) and can use the service account secrets (with domain-wide delegation). Sorry that the Google auth is a bit of a complex thing :)
I didn't understand how did you resolve those errors because when I was trying ALT+Enter it asking so many other options instead import packages and in those options import packages option is not there. Please help me here to get it done
Probably a Maven resolution issue with your IDE. You can try the example project linked here: blog.sebastian-daschner.com/entries/sending-emails-gmail-api-java This should work.
I followed this guide however, after 7 days the token expired. How would i renew it? i did take a new json file from the credential page but still gets 400 error "Invalid_grant" token expired error.
Good question :) I guess the API offers the full Gmail features (some of which might not be in the SMTP protocol) if we're talking about one's own account. For impersonating users I think this is only possible via API... If you already have a working smtp access then just sending yourself (or someone) an email might be not worth it to switch that to the API, but in general (starting from zero) I found it easier to integrate the API access into an application.
As of 2023 you cannot send an e-mail from a program using SMTP and using Gmail if you have a basic, free Google account. I think Google has inaccurate (old) documentation on this topic. Anyway, I tried the SMTP approach and I'm getting the error: "535-5.7.8 Username and Password not accepted."
@@GrantMitchell-f2p App passwords are no longer supported by Google when using free account. When did you tried creating app password in Google last time?
@@GrantMitchell-f2pthis works in 2024? Meaning javax library and the app generated google password? Because I still get some errors when using it in android. On STMP Tool online ot works tho..
Dazu benötigt man evtl einen service account. Siehe developers.google.com/identity/protocols/oauth2/service-account (die domain-wide delegation funktioniert aber IIRC nur mit einem GSuite / Admin account)
I still have a question that I couldn't solve myself: how to use queries to get email with a specific header? E.g. I need one email with needed for me X-custom-header, but I couldn't make it work like: service.users().messages().list(ME).setQ("X-custom-header:someInt");
Good question. I've tried this myself and couldn't list messages by specific headers, neither in the API nor in the Gmail search. This page support.google.com/mail/answer/7190?hl=en lists the available search criteria (what you can put into the `?q=` param), and a header isn't part of it. I think that's not possible that easily. Maybe a way would be to use a Gmail filter or functionality to put the message into a label...
When I run the code, I get: java.lang.RuntimeException: Unable to start activity ComponentInfo ...: java.lang.RuntimeException: java.io.IOException: unable to create directory: /tokens Am I supposed to create this folder, or maybe an android application (aka assets instead of res) needs another approach?
I am not going to bully you on this but it's kind of self explanatory. It is looking at the path /tokens which is in the resource folder. If you don't see it then you do not have the tokens folder which means you need to make it. :)
@@SebastianDaschnerIT are you app working with this requirements as below Ability to send emails to a list of email addresses (unlimited) Ability to set different subjects for a series of emails Ability to set different content for a series of emails Ability to send emails with text template Offering reports on the success or failure of each email Ability to determine pause between emails Ability to use multiple gmail api accounts for sending emails Ability to set the number of emails sent per account Ability to switch accounts Ability to switch proxies
Kind of. Yes it would work, but if you distribute it to others, that's likely not what you want, since then those users had access to your token (and email account). For accessing email on behalf of a user, they need to go through the OAuth thing, then. If you only create an app for yourself it works.
@@SebastianDaschnerIT Thanks. This would be for personal use. Since gmail app is already on the phone, isn't there a way to have your app have gmail app send the email? The important thing for me is that it should happen without any user interaction (no UI involved), as my app will need to run forever in the background.
Yes, these will be some questions to solve; I'm not an Android expert, but what I'd do is to have a minimal working example with Gmail just as plain Java (in your IDE), and then have a minimum android app example that does the job (and just log it first) and the put everything together and insert it into the app secondly.
@@SebastianDaschnerIT Followed a different video & got sending ermail by directly connecting to google's SMTP server working. Downside is you need your gmail username/password in the app. Should be ok for personal use. The other risk is you never know when google will pull the plug on allowing their smtp server to be used. But for now something is working for sending email on android. It's a sms-to-email-forward app. Thanks for your responses!
@@SebastianDaschnerITso then what could be done to make an app that could be distributed publicly?.. I want to retrieve the user's emails in the app using the api.
That's navigating a directory in Zsh (with some Tab expansions and I think an alias). This video should explain this: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-j9g-VfKnkoU.html
For the MIME message you can set html / multipart and then add your HTML content. Java Text blocks help here or templating approaches like Quarkus Qute
@@SebastianDaschnerIT Hi again, you wrote Set.of(GMAIL_SEND) at minute 25:03 line 46 but when I write this code , I'm getting "no found interface" error. How can i solve this
You need Java 9 + for Set.of() and to import static com.google.api.services.gmail.GmailScopes.GMAIL_SEND for the field. You can check out my code on GitHub: blog.sebastian-daschner.com/entries/sending-emails-gmail-api-java
You'd have to look into some content how to build Java sources with dependencies (that you'd need to fetch from somewhere). The dependencies are stated in my pom.xml and you can also download them directly from Maven central. Good luck with ant ;)
Hey, I am getting this error "Exception in thread "main" java.lang.NullPointerException at java.base/java.io.Reader.(Reader.java:168) at java.base/java.io.InputStreamReader.(InputStreamReader.java:76)" Can you please help me?
Do you ever read the error and look it up? Not trying to be a hard ass even tho I am lol. But seriously it is an exception saying some variable you put in the inputstream is null or something is null. Check to see if you missed a step when it comes to setting a variable.
You probably figured it out, but when you get a Null Pointer exception, in this case you are trying to access a file(credential.json file) that doesn't exist. You have to set the proper path for your file. @jalen8430
I had this same problem, and to the "hard asses out there", reading the error and looking it up doesn't help. I too was confused about the location of a file accessed by GMailer.class.GetResourceAsStream(). So, because InputStreamReader's constructor simply wants any InputStream, I replaced getResourceAsStream() with new FileInputStream("path to your json file"). And it worked. Otherwise, this video was excellent.
Can you help me with this please ? Exception in thread "main" java.lang.NullPointerException at java.base/java.io.Reader.(Reader.java:168) at java.base/java.io.InputStreamReader.(InputStreamReader.java:76) at com.cydeo.GMailer.getCredentials(GMailer.java:55) at com.cydeo.GMailer.(GMailer.java:45) at com.cydeo.GMailer.main(GMailer.java:107)
Exception in thread "main" java.lang.NoClassDefFoundError: sun/misc/ServiceConfigurationError at com.sun.net.httpserver.HttpServer.create(HttpServer.java:110) at com.google.api.client.extensions.jetty.auth@1.34.1/com.google.api.client.extensions.jetty.auth.oauth2.LocalServerReceiver.getRedirectUri(LocalServerReceiver.java:127) at com.google.api.client.extensions.java6.auth@1.34.1/com.google.api.client.extensions.java6.auth.oauth2.AuthorizationCodeInstalledApp.authorize(AuthorizationCodeInstalledApp.java:109) This error is not going anywhere. I was using jdk17 first, it shows that error then i use jdk18, error is still there. How can i solve this?
@@SebastianDaschnerIT I was using same your dependencies. It shows some error about library com.sun.net.httpserver . I was searching from 2 days on internet but didn't find answer
Did you build and run just my project as a reproducer? I'm suspecting that your setup introduces some other dependencies that collide. If you start from a working example and then try to reproduce it, you should be able to find out what's causing it
@@SebastianDaschnerIT at first i was trying in my project, it didn't work, then i created a new project with only those dependencies, it still not works.
