Question about sieves

[João Silva]

Hi

I'm having a problem related to Dovecot (version 2.2.36) sieves and I'm 
not finding information.

I'm calling a sieve with

90-sieve.conf:  imapsieve_mailbox2_name = *
90-sieve.conf:  imapsieve_mailbox2_from = SPAM
90-sieve.conf:  imapsieve_mailbox2_causes = COPY
90-sieve.conf:  imapsieve_mailbox2_before = 
file:/etc/dovecot/sieve/learn-ham.sieve

The SPAM folder have a autoexpunge set.

 From the log analysis I have a very strong suspect that the sieve is 
being called when the mails from the Spam folder are expunged, is that 
possible? Is any other imapsieve_mailbox2_causes that could be used to 
prevent that?

Thanks