Support Article
Inbound Emails delayed due to loop in processing
SA-35389
Summary
The email listener gets stuck in a loop-back condition responding to auto replies and Delivery Status Notifications, DSNs
Error Messages
javax.mail.MessagingException: A3 NO Server Unavailable. 15;
nested exception is:
com.sun.mail.iap.CommandFailedException: A3 NO Server Unavailable. 15
at com.sun.mail.imap.IMAPFolder.open(IMAPFolder.java:1045)
at com.sun.mail.imap.IMAPFolder.open(IMAPFolder.java:973)
at com.pega.pegarules.integration.engine.internal.services.email.EmailListener.openMailFolder(EmailListener.java:3523)
at com.pega.pegarules.integration.engine.internal.services.email.EmailListener.emailReceive(EmailListener.java:3654)
at com.pega.pegarules.integration.engine.internal.services.email.EmailListener.oneIteration(EmailListener.java:2872)
at com.pega.pegarules.integration.engine.internal.services.email.EmailListener.run_(EmailListener.java:2749)
at com.pega.pegarules.integration.engine.internal.services.listener.ServiceListenerBaseImpl.run(ServiceListenerBaseImpl.java:454)
at java.lang.Thread.run(Thread.java:745)
Caused by: com.sun.mail.iap.CommandFailedException: A3 NO Server Unavailable. 15
at com.sun.mail.iap.Protocol.handleResult(Protocol.java:396)
at com.sun.mail.imap.protocol.IMAPProtocol.select(IMAPProtocol.java:1184)
at com.sun.mail.imap.IMAPFolder.open(IMAPFolder.java:1030)
... 7 more
Steps to Reproduce
Not Applicable
Root Cause
A defect in Pegasystems’ code or rules:
There is a case when processing Delivery Status Notifications, DSNs, it is possible to get into a loop when responding to the status notification, if and only if, the respondent continues to send email to the listener and does not respond only one time to a specific sender.
As an example you might see the following if Debug is set on the email listener class logger. (com.pega.pegarules.integration.engine.internal.services.email.EmailListener)
DEBUG EMAIL.B17326Listener.Listener|from(pega@the_sender_email_server.com)|sub([Auto-Repl) Author@B17326 - Setting response header 'subject' to 'Re: [Auto-Reply] Re: [Auto-Reply] Re: [Auto-Reply] Re: [Auto-Reply] Re:' It is seen that the subject indicates a repeated attempt to re-send the reply to the origin, who in turn resends the reply to the email listener inbox.
In most cases it seems that the auto reply, or mailer daemon will respond once per sender and the problem is averted.
Resolution
Perform the following local-change:
The following Dynamic System Setting will prevent the problem when there is a known string in the subject line from the respondent.
Ruleset: Pega-IntegrationEngine
Purpose: Email/AutoReplySubject
Value : AUTO-REPLY (Capital letters may be a comma separated list)
Related details
- Process Delivery Status Notifications (DSNs) - Specify whether the listener is to process email messages that are Delivery Status Notification (DSN) messages. See PDN article How to create an email service that responds to AutoReply and Delivery Status Notification messages. When cleared, the listener does not invoke the email service for messages with DSNs
Published March 26, 2017 - Updated October 8, 2020
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