This is not really a FileMaker question per se. You have embedded the pictures into the database, so it is now a (much) larger file.* In order to send the database as an attachment on an email, you should zip it (Create Archive is the Finder, File command or right-click).** Depending on what format your pictures were originally, they may or may not compress much (JPEGs are already compressed, so they don't get much smaller).
NEVER do that to a FileMaker while it is still open with the FileMaker application. Be sure to close it first.
If your Internet Service Provider does not allow large emails (many do not these days), then you can use a web site service such as,
Up to 100 MB files are free.
*The size of each picture depends on its format and dimensions, especially its format.
**If you primarily email attachments to Windows users, I'd recommend a "zipping" application which does not include the extra Mac icon files. I use CleanArchiver.