Your server was bouncing your mail and for kicks I removed you from the subscriber list. The computer or account of some Web4Lib subscriber is misconfigured, and is returning your message to you rather than to the address for errors. Notify me that it is happening. Hardware and software configuration is more difficult than rocket science. Either that, or more people are idiots than you could possibly imagine.
Someone posts a message to the list asking how to unsubscribe.
They can't remember the proper command or the address of the Web4Lib Web Site . I read the list too, and will respond to that person individually. If you simply must do something, reply to them privately . The list membership will thank you for it. We can't all be perfect.