No, there is no way that block checkers can work, plugin or otherwise; There was once an exploit to find out, but that no longer works. Please see the thread
Block checkers DO NOT work.
To check, you could always ask someone else if they appear online on their contact list when you think they have blocked you.
Remember online status checkers will only ever work if the contact your checking has allowed "All Others" in his allow list settings.
quote:
Originally posted by traxor
Although, if you are sure that somebody is still online, and you can see them as offline, aka blocked, then you can see if they're still online, using the feature on the frontpage of Messenger Mad.
Again, this will only work if the contact has allowed "All Others" on his allow list settings.