Unknown Alias - Reason for Concern?

[sanctuary_hill]

Was poking around my email account and noticed there was an email alias that was totally unknown to me.  I could delete it but was wondering before I do is there any legitimate reason it may be there? If not, how can I investigate possible hacking? In Yahoo email there is a way to check account login activity which provides date/time, location, IP address, so could check that way, but is that available in Verizon Yahoo mail? Or any other way to future investigate this alias.  Thanks in advance for your advise.  

[tns2]

A vz id?  those always exist, but shouldn't be considered aliases.  The regular alias is your choice to have or have not.  Nothing would depend on it.

[sanctuary_hill]

Thanks.  This alias is definitely not one I created.  So is this a method of hacking an email account?

[tns2]

Can't imagine how it got created.  DELETE IT.

[sanctuary_hill]

No good.  Won't let me delete it.  Get a Yahoo Mail message (even though I am logged into Verizon Yahoo) indicating:  "Sorry, you must have an active Yahoo! Mail account in order to qualify for an extra email address."  Next step?

[tns2]

Does the alias show on the Yahoo interface or is on the Verizon interface?