The Unknown senders are people that aren't listed in contacts on the iPhone. Not technically Spam - it's just people that you've either not heard from before, or saved their contact details.
iBlacklist requires the phone to be Jailbroken.
Member_2_6492660_1
Alan
Not necessarily true I thought that also but I sent a friend my phone number via email the other day and she then texted me and it came up with her phone number as the contact name
I did not have her in my contact list until after she sent me the first text message.
Also my dentist office texts me and they are not in my contacts list either and I get the text message fine.
The other day someone I was working with and did not have any info on him on my phone sent me a text and he went into the "Unknown Senders"
Like I said not sure how this is working still researching this.
Alan Hardisty
Perhaps it uses email account info too? Can't say I've ever paid it too much attention.
Having just looked through my Unknown senders - I saw a contact I know but don't have their email address in my contacts and haven't emailed them (personal address). I added their personal email to my contacts (in their existing contact info) and they then showed up in the SMS Messages.
My guess it is scans the entire phone for the sender info (email address for iPhone users configured to use iMessage with an email address or their mobile number) and if it finds the sender info, it puts in in the SMS messages and if not, then it assumes you don't know who they are and puts it under the Unknown list.
iBlacklist requires the phone to be Jailbroken.