Quarkus: 3rd party module not included in native image classpath

I'm using simplejavamail in my Quarkus application. I have both the library and its batch-module included in my pom.xml:

    <dependency>
      <groupId>org.simplejavamail</groupId>
      <artifactId>simple-java-mail</artifactId>
      <version>8.12.4</version>
    </dependency>
    <dependency>
      <groupId>org.simplejavamail</groupId>
      <artifactId>batch-module</artifactId>
      <version>8.12.4</version>
    </dependency>

My code works fine in dev environment, but after building the native image, I get this error:

org.simplejavamail.internal.moduleloader.ModuleLoaderException: Batch module not found, make sure it is on the classpath (https://github.com/bbottema/simple-java-mail/tree/develop/modules/batch-module)
        at org.simplejavamail.internal.moduleloader.ModuleLoader.loadModule(ModuleLoader.java:133)
        at org.simplejavamail.internal.moduleloader.ModuleLoader.loadBatchModule(ModuleLoader.java:95)
        at org.simplejavamail.mailer.internal.MailerGenericBuilderImpl.determineDefaultExecutorService(MailerGenericBuilderImpl.java:674)
        at org.simplejavamail.mailer.internal.MailerGenericBuilderImpl.buildOperationalConfig(MailerGenericBuilderImpl.java:319)
        at org.simplejavamail.mailer.internal.MailerImpl.<init>(MailerImpl.java:128)
        at org.simplejavamail.mailer.internal.MailerRegularBuilderImpl.buildMailer(MailerRegularBuilderImpl.java:212)

I have tried registering the BatchModule class for reflection with no success:

import io.quarkus.runtime.annotations.RegisterForReflection;
import org.simplejavamail.internal.modules.BatchModule;

@RegisterForReflection(targets = {
  BatchModule.class
})
public class LibReflectionRegister {
}

How do I fix this?

P.S. I don't know if this problem is related to this property I set to address another build error:

quarkus:
  native:
    additional-build-args: "--initialize-at-run-time=org.simplejavamail.internal.util.MiscUtil"

As you already noticed simplejavamail is not supported by Quarkus and thus requires some extra configuration to make it work in native mode.

Looking at https://github.com/bbottema/simple-java-mail/blob/ac9a42997c062cdb8f48dfa112930cc1c8d04af1/modules/simple-java-mail/src/main/java/org/simplejavamail/internal/moduleloader/ModuleLoader.java#L75-L87 my understanding is that the code is using org.simplejavamail.internal.batchsupport.BatchSupport to assess if the module is available or not. So you would need to register this class for reflection, but I am afraid this will only allow you to move past this error till you hit a different one.

Runtime initializing org.simplejavamail.internal.moduleloader.ModuleLoader might be necessary as well.