Spring Integration Mail IMAP - multiple receiver

Question

I'm using spring boot 2.2.4.RELEASE

I need to build a dynamic mail receiver because I can have several mail server where to fetch mails. The mail server must be configurable by other systems so my requirement is to be dynamically able in fetching messages.

I investigated and I liked the Spring Integration solution and its DSL (note: it's enough to me to simply download messages and their attachments, if any).

So I built this code:

String flowId = MAIL_IN_FLOW_ID_PREFIX+cpd.getIndirizzoMail();
if( flowContext.getRegistrationById(flowId) != null ) {
    flowContext.remove(flowId);
}
ImapMailInboundChannelAdapterSpec adapterSpec = Mail.imapInboundAdapter(connectionUrl.toString())
    .javaMailProperties(javaMailProperties)
    .shouldDeleteMessages(false)
    .shouldMarkMessagesAsRead(false)
    .selector(selectFunction);
if( confMailIn.isRichiedeAutenticazione() ) {
     adapterSpec = adapterSpec.javaMailAuthenticator(new CasellaPostaleAuthenticator(cpd.getUsername(), cpd.getPassword()));
}

IntegrationFlow flow = IntegrationFlows
.from(adapterSpec.get(), e -> e.poller(Pollers.fixedDelay(Duration.ofSeconds(pollingSeconds)).maxMessagesPerPoll(maxMailMessagePerPoll)))
.handle(message -> {

    logger.info("Message headers "+message.getHeaders());
    logger.info("Message payload "+message.getPayload());
})

.get();

flowContext.registration(flow).id(flowId).register();

I tried by using my gmail account. The code is able in connecting to GMAIL by imap but, when I try to simply log messages, I get this error:

A6 OK Success

2020-02-05 12:48:41,835 23412 [task-scheduler-1] DEBUG o.s.i.mail.ImapMailReceiver - Received 10 messages

2020-02-05 12:48:41,836 23413 [task-scheduler-1] DEBUG oA7 STORE 1 +FLAGS (\Flagged) .s.i.mail.ImapMailReceiver - USER flags are not supported by this mail server. Flagging message with system flag

A7 NO STORE attempt on READ-ONLY folder (Failure)

A8 CLOSE

A8 OK Returned to authenticated state. (Success)

DEBUG IMAP: added an Authenticated connection -- size: 1

2020-02-05 12:48:42,198 23775 [task-scheduler-1] ERROR o.s.i.handler.LoggingHandler - org.springframework.messaging.MessagingException: failure occurred while polling for mail; nested exception is javax.mail.MessagingException: A7 NO STORE attempt on READ-ONLY folder (Failure); nested exception is: com.sun.mail.iap.CommandFailedException: A7 NO STORE attempt on READ-ONLY folder (Failure) at org.springframework.integration.mail.MailReceivingMessageSource.doReceive(MailReceivingMessageSource.java:74) at org.springframework.integration.endpoint.AbstractMessageSource.receive(AbstractMessageSource.java:167) at org.springframework.integration.endpoint.SourcePollingChannelAdapter.receiveMessage(SourcePollingChannelAdapter.java:250)

Now it seems that by default the FOLDER is opened in READ_ONLY way and this seems to cause an error.

I'm stucked here and I can't figure out how to solve the issue.

May anybody give me a tip?

Thank you

Angelo

Answer 1

adapterSpec.get()

Issuing a get() on the spec circumvents Spring's bean initialization logic which switches the folder to read/write.

Either make the adapter a @Bean or simply remove the .get() and Spring will perform the initialization.

.from(adapterSpec, e -> ...