Only marginally related to travel but I trust you guys only!

Question is about services like www.readnotify.com and other similar companies that let you know when email you've sent gets read etc.

Here's the question: Is this service detectable by the recipients? Is there a way that a (sufficiently sophisticated) recipient can know in advance that the sender seeks verification and to bypass it? The companies claim that this info is not viewable to the recipient, but, for everything there is a way to do, right?
So, when I send an e-mail to an airline (personal e-mail account) and I tag it in order to know if it was read or not, is there a way for them to see/know it in advance and hence not open it, or make it look like they didn't (the report I would get from e.g. "readnotify" would be "not opened yet")?

Thank you!