Throttling and Blocking Email from Persistently Vulnerable Exchange Servers to Exchange Online

krish70 

That is a rather big issue. Yes Microsoft will be blocking EX2013 as it's over a year since it fell out of support.

On April 11, 2023 all support for Exchange 2013 ended.

https://learn.microsoft.com/en-us/lifecycle/products/exchange-server-2013

That said if you run out of days this year then as you get down to the last 20 days I would put in a support request for another 90 days. This will need to include a valid reason for not being off of a product that has been unsupported for the last 16 months. PG would need to look over your reasons and your plan to move off and then would decide to add more days. The quicker solution would be to install an EX2019 Server and replace the EX2013 quickly. If you need help doing that quickly contact your CSAM or your Microsoft Partner and they can help.