I'd agree with all the previous advice; I had to close my yahoo account as I was getting 20+ emails a day telling me that seven bank accounts I don't have had been hacked by spammers and the only way round it was to send all my security details by return.... Obvious spam, but very annoying, as were the dozens from Third World countries telling me that for access to my bank account I would get a percentage of £17million AND save lives in war torn countries at the same time. Just became tiresome! And don't get me started on the porno ones....... Now, I only give my email out to trusted people and always tick the box if I'm buying online to say I don't want email updates which seems to help enormously.
I'd say if it claims to be from your bank, then phone the bank to check before you do anything else and just don't open any attachments you are not expecting.
Anna