I get asked this question a lot and what I have found is people make so many mistakes when they use craigslist to advertise on. So what do you need to do to multiple post on Craigslist? First, you will need multiple phone verified accounts. If you do this yourself you will need to have a list of phone number available that you can use to verify the accounts with. The thing you need to remember is that Craigslist tracks your IP address so make sure that you don't use the same IP address for all of the accounts. 1 or 2 accounts is not a big deal but when you start doing multiple accounts your asking for them to get locked. If you plan on using more than 5 accounts you will need to line up IP addresses that you can use. Don't use free proxies. There are a lot of companies out there that sell premium proxies. One very important thing you need to remember and people make this mistake time and time again is that you need to abide by the posting guidelines. Don't post more than 1 ad per account per 48 hours. You will just get your ads ghosted. The last thing you need to know is how to create ads that won't get ghosted or your account locked. I recommend using image ads. You should try to avoid links if possible but it's not mandatory. Upload multiple copies with different names to a free photo sharing site. Then when you use it in the ad make sure to add a very light color yellow font with a bunch of wording in your niche. Doesn't have to be coherent people aren't going to read it. Just look at other ads and you will see what I mean. Hope that helps. If you want to see my full write up on multiple posting to craigslist go here: http://www.accountheadquarters.com/multiple-post-craigslist.html
how about just providing quality products/services that craigslist users want to use/see? I have a verified CL account which is used to post real ads for real people, never got banned, never had an issue. In the end, if you provide quality (not spam), you will be ahead of the game everytime.
It's more than just that. The problem is people are just clueless on what not to do. Some people may not realize they are even spamming and are just trying to promote some products. It doesn't matter if you have quality or not but how you actually post it. If you are a newb to posting you might be over posting or posting inappropriate items or just making yourself look spammy. Heck, before I understood Craigslist I was posting things for sale from a move from my house and kept getting flagged by the flag Nazis there. And everything was completely above board.
The internet has an innate 'stupid-tax', if you don't read the rules or don't do the homework, you'll get banned. That's fact for almost any popular (even unpopular haha) site. Go check some of these ads on CL spam flag, example: Provide high-quality, proper (by the book) ads and give people what they are looking for - you'll never be banned; following this simple strategy you can do well long-term.