Quite honestly - there's no way for any MTA provider (hosted, or otherwise)
to know how fast their "real world" delivery will be. The reason is
that you have no control over what each individual SMTP session is going to
encounter in the delivery process (bandwidth latency, AV scanning, RBL checks,
bad addresses, mailbox full, temporary unavailability, etc.).
Tags: traffic, load, fast, maximum, handle
Message size is
also a factor. 500,000 emails an hour works out to about 140 per second. That's
probably not a realistic number considering that many will probably not be
deliverable initially and will stack up in the retry queue.
I will tell you that we've tested the speed of VMS against other popular WinOS
mail server products, and we out-perform those that we've tested - some by a
very large margin. Our SMTP server is very effecient, and fast.