Malware

This is a little bizarre I have an iCloud email address which I've never used.
Suddenly from nowhere I received an email from a girl who I didn't know, the message was in a one syllable shouting "hello". Basically as I didn't recognise the sender I just binned It.

A week later I received another message from the same girl with another intriguing message, again I felt uncomfortable so I deleted it. Yesterday another message from same sender this time it was a lot more elaborate with flirtatious overtones - then asking me to download attachment. This set alarm bells ringing, I knew this was some form of malware,
Obviously I deleted again. What I can't understand is this was opened on my iPad Air, I thought that apple had made ISO platform safe from this form of attack - is there away to block this particular sender? And secondly how on earth did they get my iCloud email when I've never used it?

Apple protects you from malware not promiscuous email or spam. That's up to you or better yet your ISP. Mail comes to you from your same ISP regardless if it's to your Mac or iPad Air. Mark that kind of mail as spam as deleting it will not stop it from occurring again. Check with your ISP to see what kind of spam filtering they do. And of course you know better than to download anything that arrives as spam or unknown email.