how to enable mailbox in exchange online

[Rising Flight]

i am using exchange hybrid environment. 

one of my user which was onprem was earlier migrated to exchagne online. 

now we have disabled user. We have a requirement to export external contacts from this users mailbox. 

so how do i enable this users mailbox, when i login to exchagne online i cannot see the option to connect to mailbox like exchange on prem. 

 please help me how to enable the mailbox in office 365. 

Is there any way to export the external contact list from users mailbox without login to it. 

[#2 · Accepted solution]

Please enable the AD account from the On-premise AD and run Azure AD connect to sync.

the mailbox hosted on the cloud will be automatically attached back to account.

apart from this, there are other alternative methods to do the same. read below URL

https://alexholmeset.blog/2018/08/07/recover-softdeleted-mailbox/ 

[#3]

so i have enabled the account in AD and i have connected to exchange online and ran ADsync, when i type the command Get-Mailbox -SoftDeletedMailbox, i dont this user. experts guie me