I have been hacked!

I feel like I should dramatically but my hand over my heart and fall to the ground! I get up this morning and check my mail on my phone and I have 256 new emails, all of them saying Mail Delivery Failure. I had never seen anything like it! It was my more computer smart family that suggested that I was hacked, I couldn't do anything about it because I was also locked out. I called my server and reset my password and spent 20 minutes deleting all the garbage. If you received an email today from me (time stamped between 5 and 5:30 am), it was not me, I was otherwise occupied at that time. I don't understand why people would get any pleasure out of hacking into someone's elses account, but they must get something out of it!?!