Hi,
I am the first to admit that I do not know what the word "rand=" refers to in signing in to a Yahoo email account. I see the same thing when I sign in.
My reason for posting an answer here is to let you know about Beacon Spamming, since you are obviously interested in Security and Privacy.
I apologize if you are already aware of this. Yahoo uses information from everyone when using their email; unless you turn it off!
You can turn it off following this procedure:
Take a look at their updated privacy statement:
(http://privacy.yahoo.com/privacy)
About half-way down the page, in the section on cookies, you will see a link that says web beacons.
Click on the phrase web beacons.
That will bring you to a paragraph entitled "Outside the Yahoo Network." In this section you'll see a little "click here to opt out" link that will let you opt-out of their new method of snooping.
Once you have clicked that link, you are exempted.
Notice the "Success" message on the top of the next page.
Be careful because on that page there is a "Cancel Opt-out" button
That, if clicked, will *undo* the opt-out.
Also, Yahoo uses SPAM in all their emails; such as
[email protected].
If you wish to stop this, then:
For each Yahoo ID you have, or each email ID you have:
Go to Yahoo.com
Click on Mail, and sign in.
Then, click on Mail Options; top right.
Then, click on Account Information, on the left.
Fill in your password again; and Submit.
About halfway down, click on the link "Edit your Marketing Preferences".
Notice that ALL boxes are checked.
Click on the blue link "Clear All" at the bottom of all the check marks.
Then, click on the button "Save Changes".
Again, this must be done for every Yahoo ID.
Just for information:
If you wish to add or subtract from an Experts' reputation, or show appreciation or discontent with an answer, click on the "balance scales" icon by the Experts' name. You can then choose what you wish.
Best wishes,
fredg