Just enter the domain of the company and find how they structure their e-mails, whether it’s name@company; initials@company; name.surname@company etc. In some situations, this may already be enough, the right person might pop up there.
Once you got the structure of the mail on-point, you can now enter the e-mail of the person you are looking for. Just enter the name of the person you are searching for (you can find names on Linkedin/company websites) in the right structure.
If you have collected a few e-mails and want to send the same e-mail to all those recipients, the easiest and fastest way to do it by using Mixmax.com Mail Merge: https://mixmax.com/mail-merge-for-gmail-and-google-inbox
You can also use MixMax or a handful of other services such as Yesware, SideKick and so on, for tracking the opens of the e-mails you have just sent out.
Final note: Voila Norbert and Emailhunter have a limited number of searches per month based on the IP. A way around it is to use an extension like Hola and mask your IP after you reach the limit.