When sending an email I received this response Unusual activityDetected and advising me my a/c is suspended Y?

I am suspended from receiving,saving or sending mail for "up to 48 hours".Why is this,how can I prevent future suspensions and when will the suspension be lifted?
My emails are generally jokes I receive which I forward on.I can hardly believe that this innocent activity can possibly amount to "unusual activity"

This is Yahoo's help page on this problem.I just got an error message telling me that Yahoo! Mail detected unusual activity in my account and I can鈥檛 send, save or receive Mail for up to 48 hours. How do I correct the issue?
Here are a few areas to consider: 1. Have you noticed anything unusual that might suggest to you that someone else is using your account? If so, change your password on the Account Info page. You鈥檒l be asked to sign in before proceeding. * In the first section of the page, click Change Password and follow the instructions. 2. Did you send or receive many attachments in a short period of time? If so, try deleting some of the emails you sent or received in a short period of time in your Inbox or Sent folder. 3. Clear your browser鈥檚 cache and cookies.During the suspension, you have access to all email in your Inbox, personal folders and Sent folder, and to your Mail Options. You will not be able to send or receive mail or save any drafts. Email sent to your account will bounce back to the sender.

Mail account suspended for 48 hours
Yahoo think your account may have been hacked and sending out large amounts of email that been flagged as spam and you need to change your password click the link below for more info.
http://help.yahoo.com/l/us/yahoo/mail/cl...