Subject & Label
1) Clear and no misleading subject line.
2) Place a <ADV> label at the beginning of the subject line.
3) A valid return email address.
4) A physical address in all commercial email messages
5) Clear states your brand affiliates and sender information
6) Provide simple method for automatic un-subscription.
7) Handle the request within 10 business days (fortunately, we handle immediately)
8) Contains English instructions (at least)
List Management & Privacy
9) No email harvester, robot, dictionary attacks, etc.
10) Don't sell your customer information to third party (and don't buy of course)
More information can be found:
Singapore Spam Control Resource Center