I've only had two occasions to contact Surefire CS and I used email both times. Response was quick and issues resolved.
But you can never assume that your email was received. I'd expect that, just like my email sometimes filters out legit email, a large company has to use filters also. They have no incentive to ignore customers.
However, it does aggravate me that some entities will post email contact information, but invest little to no resources to actually respond. If you're not going to invest in making email useful, then don't post an email address in your contact information. But that's just my opinion.
Also, to be clear, I don't think Surefire has failed to support email communication. While my experience with their CS department is anecdotal, their reputation for excellent CS is well known.
Additionally, with all the sales on discontinued items, maybe their volume has increased. Or maybe it's seasonal. Whatever the cause, it's not unusual for there to be fluctuations in CS volume.