Thread:Bionicforce/@comment-7180588-20170726011339/@comment-61573-20170727105557

Send a notice. If no response is acknowledged within 7 days, assume permanent absence from this wikia has occurred. Then you can decide if demotion is necessary.

I think when you add a message to someone's chat wall, an email is sent instantly to their mailbox, so they should know contact has been established and a question asked.