Publish an SPF record for scripts.mit.edu

[andersk]

According to the ​Messaging Anti-Abuse Working Group, all outgoing email providers should publish ​SPF records for mailing domains. We should try to publish SPF records for scripts.mit.edu and scripts-vhosts.mit.edu.

It is not as easy to publish SPF records (which are DNS TXT records) at MIT as it is elsewhere, and it would be a particular pain if we had to change it frequently, but we have a few options.

• Publish "v=spf1 a:scripts1.mit.edu … a:scripts8.mit.edu" and assume it won’t need to change frequently—eight servers will almost certainly last for a long time.
• Ask for DNS delegation for scripts.mit.edu (which would be nice for other reasons, especially if we want to do per-locker load balancing some day).
• Publish "v=spf1 redirect=scripts.sipb.org" or something so we can serve the real record from elsewhere.
• Publish a lame SPF record like "v=spf1 ip4:18.181.0.0/16 -all".