Spam is a problem for everyone and it's just getting worse.  Enabling your Spam filter in Sitebuilder can help.

To help stop some of the spam from reaching your mailbox, try enabling your spam filter in your admin section.  Go to "Email Accounts", "Enable Spam Filter". 

Check the box above to enable the spam filter for all your email accounts. When spam filtering is enabled many spam emails will automatically be caught and deleted. It is important to remember that the spam filter will not catch all spam emails and that some legitimate email may be incorrectly identified as spam. If an email address is being blocked, but should not be, use the exclusion list to exclude that email address from the spam filter. You will receive a daily email detailing all of the email addresses that have been blocked by the filter.

Note: Spam Filter Preview: The spam filter is being made available on a preview basis. If you give it a try, let us know how it works for you.

IMPORTANT - Spam Exclusion List:

With spam filtering enabled, some emails that are not spam may be erroneously detected as spam and deleted by the system. When an email is blocked by the spam filter, the sender is notified that their email did not go through. You will receive a report of email addresses that have been blocked for spam. If there is an email address in your report that is not spam or if someone is having trouble sending email to you, add them to the spam filter exclusion list.

For more insight into what is causing the problem, please see the eWeek article on why spam is at it's peak right now. Spam Surge Linked to Russian Bot Herders