Can a Dynamic Distribution list group be created that uses a specific SMTP domain as the filter?

Hm, I hate it when I've overlooked something and Tony gets to be right 😄 Nope, we cannot use -like due to the limitation Tony mentioned. I do however have a working domain-based DDG, with the following filter:

(Get-DynamicDistributionGroup domain).RecipientFilter
((WindowsLiveID -eq '*@michev.onmicrosoft.com')

WindowsLiveID here can be used as a replacement for UPN, and does work for the filter:

[09:34:55][O365]# Get-DynamicDistributionGroupMember domain

Name RecipientType
---- -------------
HuKu UserMailbox
michev_gmail.com#EXT# MailUser

Apologies about the confusion, should have actually checked my setup first.