We currently use a Novell erve and Groupwise to host our compaies mail. Twice now in the past two weeks we've been hit hard with backscatter from a spoofed email account. On average we recieve 8,000 emails a day and roughly 80% of those are junk. When the bounce backs from the spoofed mailbox come in it brings the mail server to its knees. I am considering hosting the mail outside of here using Postini and then forwarding only the good stuff back. Are there any major drawbacks to making this migration?