Significant increase in spam

I've had a significant increase in incoming spam over the past 18 months as shown in the chart below. My incoming ham emails (emails that I want to read) are stable around 250-500 a day on average, but the number of spam emails has reached some thousand a day.

Thankfully the sorting is an automated process.

spam chart

So.. ehrm... if anyone has sent me an email expecting a response, but haven't gotten it in a timely manner; please bare with me and rather resend than get upset. On rare occasions there are false positives, deal with it ....