Andrea Cosentino created CAMEL-24434:
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Summary: camel-mail - idempotency and POP3 delete are keyed on a
sender-chosen Message-ID
Key: CAMEL-24434
URL: https://issues.apache.org/jira/browse/CAMEL-24434
Project: Camel
Issue Type: Improvement
Components: camel-mail
Reporter: Andrea Cosentino
Assignee: Andrea Cosentino
Fix For: 4.23.0
DefaultMailUidGenerator derives the UID from the Message-ID header supplied by
the sender:
{code:java}
private String generateMessageIdHeader(Message message) {
String[] values = message.getHeader("Message-ID");
if (values != null && values.length > 0) {
String uid = values[0];
return uid;
}
{code}
with a fallback to the message number when the header is absent.
That UID keys idempotent-consumer state and, for POP3, identifies which message
to delete on commit. Both are therefore aliasable by whoever sends the mail:
two messages carrying the same Message-ID collapse to one identity. The
practical effects are a message that is processed but whose sibling is never
deleted and is re-consumed on every poll, and replay of a previously seen
identifier suppressing a legitimate message.
Message-ID is chosen by the sending client and is not required to be unique in
practice, so it is not a suitable sole key for either purpose.
Proposal: disambiguate the UID - for POP3 combine the Message-ID with the UIDL,
and otherwise with a content hash - and have the delete path target the folder
entry it actually processed rather than re-resolving by UID. Keeping the
current behaviour available as an option would ease migration for routes that
depend on it.
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