Welcome, my name is XXXXX XXXXX I will assist you today!
My apologies that no one responded to you earlier.. Now that I have picked up this question your wait between responses will be much less than it has been.
We need to cover the alter vista issue first.. You were definitely
Phished for information. Anytime you receive a message talking about your account is going to be deactivated, deleted, removed.. Its 99% of the time a scam to get your login information, or your name and credit card numbers. http://forum.en.altervista.org/issue-reporting/489-site-used-phishing.html
What information did you give out when you clicked on the email you received? Just your login and password? if thats all you gave out, you will want to immediately go back to altervista, and change your password, and double check your security information to make sure no one changed it ..
Once we have covered the altervista account or website you have, we can move on and discuss your mac mail and t he deleted messages..
( some information that will help is, what version of mac osx do you have.. 10.6 10.7 10.8 10.9 , and what version of mail are you running?
Thank you for your patience, and I look forward to assisting you with the other 2 parts of your question.