I was about to write an article few weeks back that Microsoft doesn’t support dynamic email aliasing but they announced in Microsoft Ignite 2019 that they will support + character in Exchange Online and feature will be rolled out next year. Gmail (G-Suite) already supports this feature and if an email address is firstname.lastname@example.org then any email sent to email@example.com or firstname.lastname@example.org get sent to same email@example.com mailbox.
Microsoft has told organizations already using + character to keep an eye that their workflow doesn’t stop but anyone who isn’t using + character in their email address should wait for the deployment and shouldn’t start using it yet.
Please visit this page for more details :
Ref : https://techcommunity.microsoft.com/t5/Exchange-Team-Blog/Exchange-Transport-News-from-Microsoft-Ignite-2019/ba-p/993417
Thank you reading !