Added another interesting blog to the Links: benjojo.co.uk

Ben builds and writes about a lot of funny small projects:

• Storing files in DNS caches
• Encoding data in dubstep music
• Building an IPv6-to-Tor gateway
• Switching SSH port based on a time-based token

Postfix provides the reject_unknown_sender_domain check which allows to only accept incoming e-mails sent from domains which actually exist.

Unfortunately there exists this one external service which uses a non-existing subdomain to send their notification e-mails. Thus all their notifications get rejected.

The following configuration allows to keep the reject_unknown_sender_domain check in place, but to exclude a specific domain from this check.

# snippet in main.cf
smtpd_sender_restrictions = check_sender_access pcre:/etc/postfix/sender_domain_verification

# exclude regex in sender_domain_verification
!/@domain\.to\.exclude\.com$/ reject_unknown_sender_domain

Your distribution might ship Postfix support for pcre matches in a dedicated package which needs to be installed separately (in the case of Debian you need to install the postfix-pcre package).

Added the following blogs to the Links:

• Thoughts on programming
• eklitzke.org
• rachelbythebay.com

Seems like the blog/RSS thing is getting traction again: It's Time for an RSS Revival (via)