Originally Posted by
Deepak070 Is is related to any app which i have installed in my fone?
This recently happened to me. I had my Windows account linked to my Twitter account, and I believe someone hacked my Twitter account (they'd sent some odd tweets from my account) and then got access to my Microsoft email account and sent out a whole bunch of spam.
If I were you I'd unlink all accounts and apps from your windows account, change the password on all accounts and enable two-step authentication on your Microsoft account (and any other accounts that support it). It's a bit of a pain, but it took me a couple of hours to get everything sorted out (I had Twitter, Google, Facbook and LinkedIn accounts all linked to my Microsoft account).
From what I've read, Twitter leaks like a sieve in terms of security, so I haven't reconnected my Twitter account. I only access Twitter through the web interface, not through any of the WP8 hubs (which require you to link it to the MS account).