This is an incredibly small thing, unless it happens to you and you’re wondering: What the What?
If the text of your e-mail messages in Outlook suddenly appears very small or VERY LARGE and you don’t remember changing any settings, you are probably the victim of your mouse wheel. I unwittingly did this the other day and was temporarily mystified. How could this be when I didn’t change any default settings? Here is the solution from Microsoft Help:
In my case, I somehow managed to roll my mouse wheel with my index finger while holding down the <ctrl> button in the body of a message. <Ctrl> is below <shift> on the keyboard – I may have been attempting to capitalize a name or beginning of a sentence. Hard to know. But that manuever zoomed me in to 200% for all messages I composed, replied to, or forwarded. I likely won’t repeat that fateful combination, but this is a good example how Microsoft Help will actually help if you take the time to search for an answer to your dilemma.
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I would just point out that, in 2010, changing the Zoom level only appears to apply to the message you are in. It doesn’t establish a default setting, and there is no option for a default setting – the default remains at 100%, unfortunately.