Question about Outlook Express

Someone other than myself has signed me up to an automated e-mail list which relays YouTube links to sermons, accompanied by a written message in huge bold red type.  This organzation is named *** Email address is removed for privacy *** and has a no-reply address.

I hate to sound grumpy about this, but I'm a Hicksite Quaker, and they are a Biblical literalist hellfire and brimstone organization.  Fair enough, they're certainly entitled to freedom of religion, but I want them to quit prosetylizing to me, through automation, several times a day.  Marking them as spam in my gmail account doesn't work, the e-mails still arrive in my inbox.  Trying to unsubscribe through outlook.com doesn't work because outlook.com tells me I'm not subscribed to anything.  Unsubscribing though YouTube doesn't work, I have no YouTube account.  E-mailing them at *** Email address is removed for privacy *** doesn't work, it bounces back through mailer daemon.  Trying to open a chat doesn't work, either, as no one is ever on-line and my chat requests go unanaswered.

Does anyone have any additional ideas on how to block these repeated and intrusive messages?  I really don't want to formally complain about abuse to outlook.com or get them in any trouble.  They're entitled to prosetylize I suppose, but how the heck do I turn them off?