If you want to post using craigslist there are some things you can do to keep your self from being blocked.
1. If can use dial up, dial up gives you get a new IP address. There is also something you can get for DSL that will rotate your IP address I just can not remember what it is.
2. Use multiple email addresses.
3. Do not post link in add. Instead have a person request more information. Do not put your email address there though as you will get spam, just use the service that craigslists provides.
If you do happen to get blocked try again it about 3 days and you will fnd that you are unblocked.