There is a bug in the LinearProcessor. When a Mail is duplicted because a matcher has matched only some of the recipients, the state of the new mail for the not matched recipients is not set correctly.
Imagine the following scenario: There is a processor which is not the root processor. In this processor there is a matcher (let's call ist MatcherOne) which matches only some on the recipients of a Mail. This is followed by a matcher (let's call it MatcherTwo) which matches some or all of the recipients which were not matched by MatcherOne. The Mailet for MatcherTwo does not set the Mail's state. This is followed by more matcher-mailet-pairs.
The following ought to happen: When MatcherOne matches some of the recipients, the Mail gets duplicated. The orginal instance is sent to the mailet of MatcherOne. The duplicate for the not matched recipients is handed to the next matcher: MatcherTwo. Let's say that MatcherTwo matches all remaining recipients. Than the mailet of MatcherTwo is processed. Since this mailet does not change the state, the next matcher in the current processor should be used next.
What really happens because of the bug: When MatcherOne matches some of the recipients, the Mail gets duplicated. The orginal instance is processed correctly. The duplicate for the not matched recipients has the incorrect state "root". Nevertheless, it is handed to the next matcher of the current processor: MatcherTwo. Let's say that MatcherTwo matches all remaining recipients. Then, the mailet of MatcherTwo is processed. This mailet does not change the state, but the Mail is then treated as if that mailet had changed the state to "root". Thus the whole processing chain starts over again. This does not cause an endless loop, becauce when the Mail will reach the processor where all this happened again, MatcherOne will match all remaining recipients, so that no further duplication of the Mail will take place. The Mail will than complete the processing chain. But some matchers and mailets from before this point will have been called twice. In most cases, this might remain unnoticed, but if those mailets do stuff like adding footers, those footers are added twice.
to the constructor MailImpl(Mail,String) or add
to the service method of LinearProcessor.
I don't know which fix might be preferrable.