smtpd_recipient_restrictions = permit_mynetworks,permit_sasl_authenticated,reject_unauth_destination,check_policy_service unix:private/spfpolicy
*) It's not recommended to modify smtpd_recipient_restrictions unless you exactly know what you're doing.
*) Amavisd provides SPF verification.
and when I send email from my other email (outside my iRedMail server), I never receive email at postmaster@blahblah.net. I get these maillog:
Apr 23 09:49:41 myhost postfix/smtpd[4186]: connect from unknown[16.143.82.248]
Apr 23 09:49:42 myhost postfix/spawn[4193]: warning: command /usr/bin/python exit status 1
Apr 23 09:49:42 myhost postfix/smtpd[4186]: warning: premature end-of-input on private/spfpolicy while reading input attribute name
Apr 23 09:49:43 myhost postfix/spawn[4193]: warning: command /usr/bin/python exit status 1
Apr 23 09:49:43 myhost postfix/smtpd[4186]: warning: premature end-of-input on private/spfpolicy while reading input attribute name
Apr 23 09:49:43 myhost postfix/smtpd[4186]: warning: problem talking to server private/spfpolicy: Connection reset by peer
Apr 23 09:49:43 myhost postfix/smtpd[4186]: NOQUEUE: reject: RCPT from unknown[16.143.82.248]: 451 4.3.5 Server configuration problem; from=<blah@my-other-email.com> to=<postmaster@blahblah.net> proto=ESMTP helo=<nk11p08mm-asmtp002.mac.com>
Apr 23 09:49:43 myhost postfix/smtpd[4186]: disconnect from unknown[16.143.82.248]
It's pretty clear that your spfpolicy has some problem. You should fix it yourself since iRedMail doesn't ship it.