How to filter out blank spam emails?

[alfaniner]

On my Yahoo account, I keep getting emails in my bulk folder with no sender, and "[none]" for the subject. I don't open them but they are very small. I can't set a filter to immediately Trash them for a non-existent sender, and filtering for "[" doesn't work, because I think that' just added by Yahoo and not the actual subject.

Any suggestions? I get two or three of these a day and I don't want to see them at all.

 

[Beady]

Can you filter on wildcards? I'm thinking something along the lines of "If [Subject/Sender] does not contain [whatever]...

 

[Soapy Sam]

Don't know specifics of Yahoo. In Hotmail I use an inclusive safe list rather than exclusive filters. ie if the sender is not on the list, it goes to the junk folder.
One result of this approach is that you will not get mail from anyone new unless they call first with their email address. You may see this as a pro- or a con-, depending on personal requirements.

 

[Luciana]

Ok, now I demand an explanation!

This is what came into my inbox today. And Gmail is not identifying it as spam (at least, not yet).

 

[Dark Jaguar]

I think you just got spammed by "All the A words in the dictionary Industries".