When you upgrade to new phones, do you lose all your contacts or mail messages (and Drafts) and do you have to reset passwords?

If upgrading to the same type of phone (android to android, apple to apple) then nothing need be lost. Make sure your phone is backed up so that all that was on the old phone can be transferred to the new phone. Passwords should not need to be reset either. 
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You may want to research how data is transferred between one phone and another, based on the type of phone you use. Data can be transferred between apple and android phones, but there are extra steps (research if needed). .
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