Question about sieves

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