How does one block "undisclosed-recipients" spam email?

First...you do NOT have to put anything in the TO line when you send an email...that is how you get UNDISCLOSED-RECIPIENTS....

Now...your other answer

Usually just clicking on SPAM when you receive the message will direct it to your SPAM FOLDER and any subsequesnt emails from this person will go there...if that doesn't work try below....

If you are using yahoo classic OR all new mail.....

Go to "Options" It is above your email

Click on "Mail Options"

Click on SPAM

Enter the address you want to block

Click on “Add Block”

On occasion the sender changes their name BEFORE @ so block that DOMAIN the following way...

If you are receiving several emails from the same domain, but various ID's, the easiest way to stop them is to enter the domain into your "Blocked Addresses".

In Yahoo! mail, to block the senders domain (hotmail.com):

◘ Click on "Options, upper right corner of mail page".

◘ Then "Mail Options".

◘ Click on "Spam" from the list on the left.

◘ In the "Add a blocked address" box, enter the domain (only the part of the email address AFTER @, do not include @).

◘ Click the "Add" button.

Now, any email from that domain, no matter what ID is used to send it, will be blocked.

*

....Have a great day...................

Any E-mails you receive from "Undisclosed-Recipients" are not all necessarily spam. I get mail like that from my contacts that do not want everyone to see others names and addresses.

Besides, it is the address you are getting the mail from, that you will be blocking not who it is addressed to. here is now, I control my spam:

You can not completely stop all spam, but you can help to put a big dent in it.

First, try not to open any of them, that only makes them send more and more to you.

Check mark them and click on 'Spam,' this should stop those addresses from being delivered to your inbox.

Use your spam filter and block address.

Look for the 'Options' link at upper right corner of mail screen and click on it

Options/ mail options / spam preferences

make sure spam guard is on, click on save changes

Options /mail options / blocked addresses

Enter the E-mail address you wish blocked and click on 'add block'

you will never get mail from that address again.

This should help you to control your spam.

Other tips:

Never open E-mail unless you are absolutely sure who it is from.

Never give out your personal information to anyone.

If you are on a site and you absolutely have to sign up for something, check the entire page to make sure you uncheck any lines wanting to send you any other info, notices, catalogs, ads, and the like.

Added detail:

Yes, spammers change one item in their addresses a lot, so you might try blocking the entire domain, by putting in

*@ thedomainyouwanttoblock.com

for instance: *@seeyou.com

Hope this helps.

All emails to "Undisclosed-Recipients" are not necessarily from spammers.

Normal people sometimes put ALL addresses on the BCC line (blind courtesy copy), to protect the identity and privacy of their recipients---and the mail will be delivered showing TO Undisclosed-Recipients.

Unfortunately---Spammers could do the same.

The important thing to watch for, is--- who is the sender?

IF you don't recognize the sender as one of your friends--family--or contacts etc., then just delete it--or "Spam" it--cause it could be a spammer.

Just a remark. but I dont get all the spam on Outlook that I get on Yahoo. SO its YAhoo. I suggest changing your email to a less greedy company. YAhoo sells info to marketers. And then wonder why they get hacked lol

Go to your spam, mark the emails you want to take out of spam and then click not spam

need more details