I found a slew of entries in my event log that stated the following:

Pop3ServerError:
System.Exception: Received negative response from POP3 server <br> at Lesnikowski.Pawel.Mail.Pop3.Pop3.ReceiveLine() in C:\Dev\DasBlog CE\source\Lesnikowski.Pawel.Mail.Pop3\Pop3.cs:line 165 <br> at Lesnikowski.Pawel.Mail.Pop3.Pop3.Login() in C:\Dev\DasBlog CE\source\Lesnikowski.Pawel.Mail.Pop3\Pop3.cs:line 71 <br> at newtelligence.DasBlog.Web.Services.MailToWeblog.Run() in C:\Dev\DasBlog CE\source\newtelligence.DasBlog.Web.Services\MailToWeblog.cs:line 225
while processing

Looks like someone was attempting to post blogs into my site through the MailToBlog feature. I would be very curious to know why someone would try to do that.