Company IT unsubscribing users?

I sent out a campaign to a group of users of our product. Almost immediately, 30 people from one company showed up as blacklisted. I gave the lead at this company a phone call and he was totally baffled by this and that he would check with his IT department.

Under the statistics, they appear as having “clicked” unsubscribed. Apparently none of them did this. Does this sound familiar to anyone? Anything we can do about it?

@CAVUCO This sounds similar to problems reported earlier, see Users reporting unauthorized unsubscribes which has two suggestions.