Hello,
i dont know where else to inform you that devnetsandbox.cisco.com is missing a valid SPF entry on its domain wich causes mail servers with spf check enabled to not accept emails.
to check it:
nslookup
set type=txt
devnetsandbox.cisco.com
compared to cisco.com
cisco.com text = "v=spf1 redirect=spfa._spf.cisco.com"
/var/log/maillog:Nov 30 09:09:45 xxxxxx postfix/cleanup[439943]: B16DF1D9: milter-reject: END-OF-MESSAGE from alln-smtp-ext-1.cisco.com[173.37.147.244]: 5.7.23 SPF validation failed.; from=<no-reply@devnetsandbox.cisco.com> to=<xxxxxxxxx> proto=ESMTP helo=<alln-smtp-ext-1.cisco.com>
