View Email Images
Yes it can be happen because of the other pictures available on your computer. Here when you try to open an Images which is of your email the main problem arise when you already surf on internet a lot before you open the particular photo and when you open the particular photo of your email your windows image viewer open other images too which you have already viewed before while you are surfing on internet. The main reasons for this is "Cache of your browser". Everytime when you surf or open the particular iamge or picture it has been in cache memory till you didn't delete or remove it or you didn't restart you computer. Then when ever you open an email photo that pgoto also go to the cache memory of your computer first and then it open but because there are lot of photos too in the cache memory so i might be able to view all the photos which is on cache memory along with the emailed Pictures.
The other reason might be the Name of your Photo which the email sender sent you if you have another image with the same name then you can be possible that the recent photo which you got in email can be named as postfix of some character or number along with the specified name by email sender, Then also your windows picture viewer may get confused and open up both the images.
Another reason is the algorithms used to decode the encoded image it may be possible that alogorithm decode the wrong image and open up the pictures which might be having same data format.
There are more reasond which can be responsible to make view other pictures on images view other than emailed photos.
if you have got an html format email then it may be possible that the particular email contain some images with having attractive border, rounded squares, rounded rectangles those photo not made up with single photos but actually they are the embedded collection of number of photos and when you try to view those photo your image viewer open those all photos separately and you think that the emailed photo not showing up properly.
It may be possible that the pop ups having some images and those images try to open up with the default image viewer, If you block pop up windows from window setting may restrict them to open it from the image viewer.