Could be that the file size for your pictures are just too large for emailing. Generally, as email attachments, they should total less than 1 MB. If that is the problem, do a "RESIZE PICTURES" of each photo to get each of the photos down into the 30 to 80 KB range. The pictures will look just as good, and you will be able to send a bunch of them in a single email without reaching the 1 MB limit..
The "RESIZE PICTURES" function is available under Windows XP. Just go to the folder where the picture is stored, right click on a picture, then click the "RESIZE PICTURES" and choose "medium" or "small". Your old {large file) picture will not be altered, but a new copy of the picture will be created and will contain the word "medium" or "small" in the file name. Those pictures will be a heck of a lot smaller in file size, appropriate for emailing as attachments.
If this is not the problem, maybe my post will help someone else - hopefully.
Regards.