To create a contact on Exchange 2010, 2013 & Exchange Online using EMS the command is:
New-MailContact -DisplayName "Display Name" -ExternalEmailAddress "[email protected]" -Name "Alias"
To create contacts from a list, using a bulk command first create a csv file with th contacts. The csv must have the Display Name, the Email Address and the alias for each contact. The run the below command:
Import-Csv C:tempcontacts.csv|%{New-MailContact -Name $_.alias -DisplayName $_.DisplayName -ExternalEmailAddress $_.EmailAddress}

Pantelis Apostolidis is a Cloud Solutions Architect at Microsoft and an ex Microsoft Azure MVP. For the last 15 years, Pantelis has been involved to major cloud projects in Greece and abroad, helping companies to adopt and deploy cloud technologies, driving business value. He is entitled to a lot of Microsoft Expert Certifications, demonstrating his proven experience in delivering high quality solutions. He is an author, blogger and he is acting as a spokesperson for conferences, workshops and webinars. He is also an active member of several communities as a moderator in azureheads.gr and autoexec.gr. Follow him on Twitter @papostolidis.