If you need to add email aliases to O365 accts in bulk use the following (EMS) powershell command with the CSV file formatted this way:
| Name | ProxyAddresses |
| user1@domainold.com | user1@domainnew.com |
Run this in EMS:
Import-Csv C:\email-aliases.csv | ForEach-Object{ $name = $_.Name }
Import-Csv C:\email-aliases.csv | ForEach-Object{ $proxy = $_.ProxyAddresses -split ‘;’}
Set-RemoteMailbox -Identity $name -EmailAddresses @{add= $proxy}
OR
Get the display name and email alias in this CSV format.
| mailbox | newemailaddress |
| Phyliss Ames | pames@email.domain.com |
| Shelley Whitten | swhitten@email.domain.com |
Run in EMS:
Import-CSV “C:\staging\aliases2.csv” | ForEach {Set-RemoteMailbox -identity $_.Mailbox -EmailAddresses @{add=$_.NewEmailAddress}}