it seems that office 365 and exchange now support it :
According to microsoft website (see link below)
From September 2020, plus addressing, also known as subaddressing, is available in Exchange Online. Subaddressing is a defined way to support dynamic, disposable recipient (not sender) email addresses for mailboxes.
An SMTP email address uses the basic syntax: @. For example, sean@contoso.com.
Plus addressing uses the syntax: +@. For example, sean+newsletter@contoso.com.
The original email address must be valid; the +tag value that you add is arbitrary, although regular character restrictions for SMTP email addresses apply (for example, no spaces). For more information about using plus addresses, see Using plus addresses.
Plus addressing is available in Outlook. By default, plus addressing support is disabled in Exchange Online. Since Exchange Online has always supported regular email addresses that already contain the plus sign, if you enable plus addressing, these email addresses might stop working.
If your organization's email is routed through Exchange Online to your on-premises servers, mailboxes hosted on-premises will also be able to use plus addresses.
Use the new Exchange admin center to enable plus addressing
In the new Exchange admin center, go to Settings > Mail flow.
Select Turn on plus addressing for your organization, and then select Save.
https://docs.microsoft.com/fr-fr/exchange/recipients-in-exchange-online/plus-addressing-in-exchange-online