Troubleshooting Email Connector - Mule 4

To troubleshoot Anypoint Connector for Email (Email Connector), become familiar with the information about app logs, JavaMail debugging, troubleshooting access attachments, troubleshooting protocols issues, and interpreting commonly thrown messages.

View the App Log

If you encounter problems while running your Mule runtime engine (Mule) app, view the app log as follows:

If you’re running the app from Anypoint Platform, the output is visible in the Anypoint Studio console window.
If you’re running the app using Mule from the command line, the app log is visible in your OS console.

Unless the log file path is customized in the app’s log file log4j2.xml, view the app log in the default location MULE_HOME/logs/<app-name>.log.

Enable JavaMail Debug Logging

JavaMail debugging logging is used by underlying third-party classes.

To enable JavaMail debugging logging:

Access Anypoint Studio and navigate to the Package Explorer view.
Open your application’s project name.
Open the src/main/mule path folder.
Open your Mule app XML file inside the folder.

Add the <property key="mail.debug" value="true"/> to the IMAP or SMTP connection element.

  <email:imaps-connection host="..." user="..." password="..." >
    <email:properties >
      <email:property key="mail.debug" value="true" />
    </email:properties>
  </email:imaps-connection>

Save your changes.
Click the project name in Package Explorer and then click Run > Run As > Mule Application.

Navigate to the Console view to read the email messages in the logger:

DEBUG: JavaMail version 1.6.3
DEBUG: successfully loaded resource: /META-INF/javamail.default.address.map
DEBUG: getProvider() returning javax.mail.Provider[STORE,imap,com.sun.mail.imap.IMAPStore,Oracle]
DEBUG IMAP: mail.imap.fetchsize: 16384
DEBUG IMAP: mail.imap.ignorebodystructuresize: false
DEBUG IMAP: trying to connect to host "******", port 993, isSSL true
* OK The Microsoft Exchange IMAP4 service is ready. [******]
A0 CAPABILITY
* CAPABILITY IMAP4 IMAP4rev1 AUTH=PLAIN AUTH=XOAUTH2 SASL-IR UIDPLUS MOVE ID UNSELECT CHILDREN IDLE NAMESPACE LITERAL+
A0 OK CAPABILITY completed.
...

If you run the app in Anypoint Studio, the logging prints the debug lines in the console view.
If you run the app in a standalone Mule, the logging prints the debug lines in the log file.

Enable Email Connector Debug Logging

To begin troubleshooting Email Connector, enable debug logging to see the exact error messages:

Access Anypoint Studio and navigate to the Package Explorer view.
Open your application’s project name.
Open the src/main/resources path folder.
Open the log4j2.xml file inside the folder.
If the following line is already in the log4j2.xml file, uncomment it to enable it; otherwise, add it:
```
<AsyncLogger name="org.mule.extension.email" level="DEBUG" />
```
Save your changes.
Click the project name in Package Explorer and then click Run > Run As > Mule Application.

Navigate to the Console view to read the Email Connector’s messages in the logger:

DEBUG 2021-04-26 18:51:08,536 [_pollingSource_imapattachmentFlow/executor.01] [processor: ; event: ] org.mule.extension.email.internal.mailbox.BaseMailboxPollingSource: Poll will be skipped, since last poll emails are still being processed
INFO  2021-04-26 18:51:09,166 [[MuleRuntime].uber.04: [imapattachment].imapattachmentFlow.CPU_LITE @111719e0] [processor: imapattachmentFlow/processors/1/processors/2; event: 820f7fe0-a6d9-11eb-a84b-147dda4dba09] org.mule.runtime.core.internal.processor.LoggerMessageProcessor: "" as Binary {base: "64"}
DEBUG 2021-04-26 18:51:15,360 [_pollingSource_imapattachmentFlow/executor.01] [processor: ; event: ] org.mule.extension.email.internal.mailbox.BaseMailboxPollingSource: Email [172] was not processed.
....

Troubleshoot SMTPS and Gmail Connection Issues

The method that you use to troubleshoot SMTPS connection issues depends on whether or not your Gmail account uses two-factor authentication:

Two-Factor Authentication

If your account uses two-factor authentication value, generate an app-specific password and use that instead of your normal password. See Sign in Using App Password for details. You do not need to enable Less Secure Apps in your Gmail account.

Password-Based Authentication

If your Gmail account does not use two-factor authentication, set up and enable Less Secure Apps in your Gmail account, and if your password does not work, go to Allow Access to Your Google Account and follow these steps:

Enter your username and password.
Enter the letters on the captcha screen.
Return to your Mule app and rerun the flow.

Understand the Behavior of the Different Protocols

If your problem is protocol behavior, check the RFC documents. A Request for Comments (RFC) is a publication from the Internet Society (ISOC) and its associated bodies, most prominently the Internet Engineering Task Force (IETF), the principal technical development and standards-setting bodies for the internet. The IETF adopts some of the proposals published as RFCs as internet standards. Some documents that you can check are:

Understand Common Throws

Here is a list of common throw messages and how to interpret them:

EMAIL:EMAIL_NOT_FOUND

The email identified by `emailId` cannot be found in a mailbox folder.

EMAIL:ACCESSING_FOLDER

There was a problem accessing an email folder or the folder does not exist.

EMAIL:CONNECTIVITY
```
A connection could not be established.
```

EMAIL:RETRY_EXHAUSTED

A problem occurred during message routing.

EMAIL:EMAIL_LIST

An error occurred during an attempt to list emails.

EMAIL:SEND

An exception occurred during an attempt to send an email.

EMAIL:FETCHING_ATTRIBUTES

An error occurred during email attribute parsing from an email.

EMAIL:MARK

An error occurred during email flag marking.

EMAIL:EXPUNGE_ERROR

A error occurred during an attempt to delete emails from a folder.

EMAIL:ATTACHMENT

An error occurred during an attempt to send an attachment.

EMAIL:READ_EMAIL

An error occurred during an attempt to read the email content.

EMAIL:AUTHENTICATION
```
Authentication failed.
```

EMAIL:INVALID_CREDENTIALS

An error occurred during the username and password parameter consistency check.

EMAIL:UNKNOWN_HOST

The IP address of a host cannot be determined or a port is out of range.

EMAIL:CONNECTION_TIMEOUT

The server took too long to reply to a data request.

EMAIL:DISCONNECTED

An error occurred during store connecting, or the connection was interrupted.

EMAIL:SSL_ERROR

An error occurred during SSL context creation, or the TLS context wasn't properly configured.