The problem is solved!!!!

In the library "src/lib-sieve/plugins/vacation/cmd-vacation.c", in the
package "dovecot-sieve" or "dovecot-pigeonhole" modify:

 smtp_handle = sieve_smtp_open(senv, reply_to, NULL, &f);
 smtp_handle = sieve_smtp_open(senv, reply_to, reply_from, &f);

You can check the correct operation in your logs.

/var/log/maillog

postfix/smtpd[27112]: connect from smtp.mydomain.com postfix/smtpd[27112]: A95D2168456: client=smtp.mydomain.com postfix/cleanup[27114]: A95D2168456:
message-id=<A5BBC98AAF65424CADBFB6ACF0003E8B03FB4B74@example.com> postfix/smtpd[27112]: disconnect from smtp.mydomain.com postfix/qmgr[17010]: A95D2168456: from=<asier.cidon@example.com>,
size=7274, nrcpt=1 (queue active) postfix/pipe[27115]: A95D2168456: to=<asier.cidon@mydomain.com>,
relay=dovecot, delay=0.09, delays=0.01/0/0/0.08, dsn=2.0.0,
status=sent (delivered via dovecot service) postfix/qmgr[17010]: A95D2168456: removed

/var/log/dovecot.log

dovecot: auth(default): master out: USER 1 asier.cidon@mydomain.com
uid=xxx gid=xxx quota_rule=*:bytes=524288000 home=/buzon/asier.cidon dovecot: deliver(asier.cidon@mydomain.com): sieve:
msgid=<A5BBC98AAF65424CADBFB6ACF0003E8B03FB4B74@example.com>: sent
vacation response to <asier.cidon@example.com> dovecot: deliver(asier.cidon@mydomain.com): sieve:
msgid=<A5BBC98AAF65424CADBFB6ACF0003E8B03FB4B74@example.com>: stored
mail into mailbox 'INBOX'

/var/log/maillog

postfix/pickup[17009]: B221D168458: uid=xxx from=<asier.cidon@mydomain.com> postfix/cleanup[27114]: B221D168458:
message-id=<dovecot-sieve-1344420404-703760-0@mda.mydomain.com> postfix/qmgr[17010]: B221D168458: from=<asier.cidon@mydomain.com>,
size=661, nrcpt=1 (queue active) postfix/smtp[27195]: B221D168458: to=<asier.cidon@example.com>,
relay=smtpinterno.mydomain.com, delay=0.04, delays=0.01/0/0.01/0.01,
dsn=2.0.0, status=sent (250 2.0.0 Ok: queued as A3A092280B3) postfix/qmgr[17010]: B221D168458: removed