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  1. Red Hat build of Keycloak
  2. RHBK-3415

Can't send e-mails to international e-mail addresses: bad UTF-8 syntax [GHI#41023]

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      Area

      login/ui

      Describe the bug

      When attempting to send an e-mail to an international e-mail address from Keycloak, the following error appears in the log:

      Jul 09 10:26:42 login docker[1200]: jakarta.mail.SendFailedException: Invalid Addresses;
Jul 09 10:26:42 login docker[1200]:   nested exception is:
Jul 09 10:26:42 login docker[1200]:         org.eclipse.angus.mail.smtp.SMTPAddressFailedException: 500 5.5.2 Error: bad UTF-8 syntax
Jul 09 10:26:42 login docker[1200]:         at org.eclipse.angus.mail.smtp.SMTPTransport.rcptTo(SMTPTransport.java:2097)
Jul 09 10:26:42 login docker[1200]:         at org.eclipse.angus.mail.smtp.SMTPTransport.sendMessage(SMTPTransport.java:1291)
Jul 09 10:26:42 login docker[1200]:         at org.keycloak.email.DefaultEmailSenderProvider.send(DefaultEmailSenderProvider.java:86)
Jul 09 10:26:42 login docker[1200]:         at org.keycloak.email.DefaultEmailSenderProvider.send(DefaultEmailSenderProvider.java:72)
Jul 09 10:26:42 login docker[1200]:         at org.keycloak.email.freemarker.FreeMarkerEmailTemplateProvider.send(FreeMarkerEmailTemplateProvider.java:289)
Jul 09 10:26:42 login docker[1200]:         at org.keycloak.email.freemarker.FreeMarkerEmailTemplateProvider.send(FreeMarkerEmailTemplateProvider.java:283)
Jul 09 10:26:42 login docker[1200]:         at org.keycloak.email.freemarker.FreeMarkerEmailTemplateProvider.sendSmtpTestEmail(FreeMarkerEmailTemplateProvider.java:128)
Jul 09 10:26:42 login docker[1200]:         at org.keycloak.services.resources.admin.RealmAdminResource.testSMTPConnection(RealmAdminResource.java:1148)
Jul 09 10:26:42 login docker[1200]:         at org.keycloak.services.resources.admin.RealmAdminResource$quarkusrestinvoker$testSMTPConnection_0bc3cac9c894e7b29eb4c1f2d80a099cba7bdf38.invoke(Unknown Source)
Jul 09 10:26:42 login docker[1200]:         at org.jboss.resteasy.reactive.server.handlers.InvocationHandler.handle(InvocationHandler.java:29)
Jul 09 10:26:42 login docker[1200]:         at io.quarkus.resteasy.reactive.server.runtime.QuarkusResteasyReactiveRequestContext.invokeHandler(QuarkusResteasyReactiveRequestContext.java:141)
Jul 09 10:26:42 login docker[1200]:         at org.jboss.resteasy.reactive.common.core.AbstractResteasyReactiveContext.run(AbstractResteasyReactiveContext.java:147)
Jul 09 10:26:42 login docker[1200]:         at io.quarkus.vertx.core.runtime.VertxCoreRecorder$15.runWith(VertxCoreRecorder.java:638)
Jul 09 10:26:42 login docker[1200]:         at org.jboss.threads.EnhancedQueueExecutor$Task.doRunWith(EnhancedQueueExecutor.java:2675)
Jul 09 10:26:42 login docker[1200]:         at org.jboss.threads.EnhancedQueueExecutor$Task.run(EnhancedQueueExecutor.java:2654)
Jul 09 10:26:42 login docker[1200]:         at org.jboss.threads.EnhancedQueueExecutor.runThreadBody(EnhancedQueueExecutor.java:1627)
Jul 09 10:26:42 login docker[1200]:         at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1594)
Jul 09 10:26:42 login docker[1200]:         at org.jboss.threads.DelegatingRunnable.run(DelegatingRunnable.java:11)
Jul 09 10:26:42 login docker[1200]:         at org.jboss.threads.ThreadLocalResettingRunnable.run(ThreadLocalResettingRunnable.java:11)
Jul 09 10:26:42 login docker[1200]:         at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
Jul 09 10:26:42 login docker[1200]:         at java.base/java.lang.Thread.run(Thread.java:1583)
Jul 09 10:26:42 login docker[1200]: Caused by: org.eclipse.angus.mail.smtp.SMTPAddressFailedException: 500 5.5.2 Error: bad UTF-8 syntax
Jul 09 10:26:42 login docker[1200]:         at org.eclipse.angus.mail.smtp.SMTPTransport.rcptTo(SMTPTransport.java:1997)
Jul 09 10:26:42 login docker[1200]:         ... 20 more

      Using the "Enable Debug SMTP" option in Realm Settings > Email > Connection & Authentication, we can see that Keycloak does not encode the address properly when communicating with the SMTP server, replacing "öüä" with "���" 

      Jul 09 10:26:42 login docker[1200]: DEBUG SMTP: AUTH LOGIN succeeded
Jul 09 10:26:42 login docker[1200]: DEBUG SMTP: use8bit false
Jul 09 10:26:42 login docker[1200]: MAIL FROM:<keycloak@test.com>
Jul 09 10:26:42 login docker[1200]: 250 2.1.0 Ok
Jul 09 10:26:42 login docker[1200]: RCPT TO:<test+���@test.com>
Jul 09 10:26:42 login docker[1200]: 500 5.5.2 Error: bad UTF-8 syntax
Jul 09 10:26:42 login docker[1200]: DEBUG SMTP: Invalid Addresses
Jul 09 10:26:42 login docker[1200]: DEBUG SMTP:   test+öüä@test.com
Jul 09 10:26:42 login docker[1200]: DEBUG SMTP: Sending failed because of invalid destination addresses
Jul 09 10:26:42 login docker[1200]: RSET
Jul 09 10:26:42 login docker[1200]: 250 2.0.0 Ok
Jul 09 10:26:42 login docker[1200]: DEBUG SMTP: MessagingException while sending, THROW:
Jul 09 10:26:42 login docker[1200]: jakarta.mail.SendFailedException: Invalid Addresses;

      Version

      26.2.4 (can be reproduced in 26.3.0 as well)

      Regression

      [ ] The issue is a regression

      Expected behavior

      E-mails can be sent to international e-mail addresses containing UTF-8 characters

      Actual behavior

      When trying to send an e-mail from Keycloak to an international e-mail address, e.g. password reset/verify email actions or by using the "Test connection" button in Realm Settings > Email > Connection & Authentication, "Error! Failed to send email" is shown in the UI, and org.eclipse.angus.mail.smtp.SMTPAddressFailedException: 500 5.5.2 Error: bad UTF-8 syntax appears in the Keycloak logs on the server` is shown in the Keycloak log on the server.

      How to Reproduce?

      1. Create a user with an international e-mail address, assign the "Verify e-mail" required action and set a password
      2. Attempt to log in with the user
      3. A "Failed to send email" error appears
      4. org.eclipse.angus.mail.smtp.SMTPAddressFailedException: 500 5.5.2 Error: bad UTF-8 syntax appears in the Keycloak logs on the server

      Anything else?

      The behavior can be reproduced with a 'real' SMTP server/relay like Postfix, as well as a 'mock' e-mail server like Maildev. In case of Maildev however, Keycloak is able to send e-mails to Maildev, but the address isn't displayed correctly in the Maildev UI
      <img width="201" height="42" alt="Image" src="https://github.com/user-attachments/assets/b12f797c-aad0-4b26-bc60-85fa0469462a" />

      My theory is that since Maildev is a 'mock' mail server, it doesn't verify e-mail addresses to the same extent as e.g. Postfix.

              Unassigned Unassigned
              pvlha Pavel Vlha
              Keycloak Core Clients
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                Created:
                Updated:
                Resolved: