Over the years, we've seen spam increase from time to time and unfortunately, it looks like we are in a particularly busy period for it right now. I'm not sure what specifically, if anything, causes these spikes, but they do seem to come and go in waves.
Unfortunately, it is very difficult to prevent, and spam-management is a reality for every online community. Most of the spam-related accounts and posts are created by a distributed, inexpensive labour force, so, as Axel mentioned, captchas and related techniques do not work. And because it only takes moments to create a new account and publish a question, it is ultimately easy for spammers to create their content. In a few rare instances, we have even seen users create multiple accounts and up-vote their posts in order to escape the "zero reputation" scenario.
In my opinion, community moderation, similar to what MaplePrimes does now, is the best way forward. We have a number of diligent users - both inside and outside of Maplesoft - who regularly patrol MaplePrimes and remove unwanted messages. These efforts are greatly appreciated, and they help keep MaplePrimes virtually spam-free for the thousands of users who visit us daily. We have tried to make the delete process as quick and simple as possible, but I can understand that it is occasionally onerous, especially for those who regularly contribute their time.
That said, there are some additional things that we can do. I particularly like Carl's suggestion to add a "delete as spam" function. When selected, this would perform multiple actions (i.e., ban the user and remove their other posts) in addition to simply removing an individual message, as is done now. We are currently working on some updates to MaplePrimes, and will add this feature to the mix.
This will certainly not eliminate the problem, and we will still get hit by spam attacks from time to time. But hopefully it will make it a bit easier to manage, and a bit harder for the spammers to do their jobs.