Hey I want to change about 500 email accounts to One of our new accepted domains. I have a list of email address in a txt file. I want to keep the first part of the email address the same so like J.C.Smith or James.Smith
it is just the @oldDomain.com i want to change to @newdomain.comand needs to be set as primary

any one got a quick script to do this as havingissues

cheers

Create CSV file with below headers

Alias,emailaddress

johnh,johnh@domain.com

Save the file as data.csv 

Use the below command

Import-Csv c:\data.csv | Foreach{set-mailbox -identity $_.Alias -EmailAddresses @{replace=$_.emailaddress}}

Hi,

Email address policy can do this.

1. In EAC, go to mail flow > email address policies.
2. Choose the email address policy applied to users. Double-click to edit it.
3. Under email address format tab, double-click on it.
4. Check Select an accepted domain, then choose that accepted domain.
5. Under email address format section, choose or customize the format what you want.
6. Click save > save to close the tab. On the right of the reading panel, click Apply to apply this change.
7. Then user will use the @newdomain.comand as primary SMTP address.

More information about email address policy.

https://technet.microsoft.com/en-us/library/bb232171%28v=exchg.150%29.aspx?f=255&MSPPError=-2147217396

Best Regards.