Composed email going to draft when I click send

I have noticed that on multiple occasions from multiple locations when I complete an email and chose send.  I will find that the email never went out and went into my drafts instead.  This happens occasionally and I thought maybe I forgot to click send.  Unfortunately, it has now been brought to my attention from another colleague.  So I know it is not just me, but because it doesn't happen all the time we are not sure how to resolve the potential problem from occurring.  Any suggestions?