SPAMHAUS is a service used to intercept spam mails from hitting industry email servers.
They have had a number of messages from your IP or email account which have been classed as spam - If they have too many they then reject all mail from you.
On the bounced messages back, it should give instructions on how to get the spam filter lifted. OR shout at your IT team at your employer and say you cannot do any work until this is sorted.
It would be worth running a complete virus scan on your workstation using an up to date scanner (AVG or Malwarebytes), both of which have free downloads on their respective websites.