If anything should happen during the emailing of a batch of forms, so that the process is interrupted, you will get the usual prompt asking "Did your forms print correctly? Do you want to assign numbers?" How you answer that depends on where you were in the emailing process. If you were near the end, you would probably want to answer Yes and let Sage 50 assign transaction numbers. Then you could check the Send folder of your email program to see which forms were successfully sent, and then remove the transaction number by going into the Task window, selecting the List button, and removing the transaction number (Invoice number, for example) for all forms that were not emailed.
If you are near the beginning of emailing a batch of forms, and the process is interrupted, you would want to answer No to the prompt asking "Did your forms print correctly? Do you want to assign numbers?" Then you could check the Send folder of your email program to see which forms were successfully sent. Then, manually add a transaction number by going into the Task window, selecting the List button, selecting the transaction, and typing the number in for those forms that sent. Then, when you start the emailing process again, make sure the starting transaction number is correct.
If you choose to preview a form, and you are emailing a batch of forms, you should close the Adobe® Reader® software once you have previewed the form. This will prevent conflicts between Sage 50, your email software, and Adobe® Reader® software.