I am doing free photo shoot for clients to build my portfolio to start my business. I would like to send my clients the photos through email via Dropbox. Can anyone tell me what would be an acceptable file size to send clients where the pictures will look sharp and if need be they can print photos. Also is there a size limit when sending photos through dropbox ?
There is no limit to file size on Dropbox.
And Dropbox doesn't involve email, except for sending a link to your client for downloading.
To share a folder on Drobox, go to dropbox.com in your web browser, then click Share next to the folder, then Create link and Copy link. Then send the link to your client.
How big prints do you want your clients to be able to make?
If you want to limit it to for instance 10 inches on the long side at 300 ppi, export at 3000 pixels on the long side. (3000:300 = 10).
You should probably export as jpg with a high quality setting - at least 85.
Since you don't know if the image is going to be printed, I would use Output sharpening for screen, standard.