@Sajid Ali Shah
Hi,
First of all,please note that Exchange 2010 has reached its end of support in October 13,2020.
It is strongly recommended to consider upgrading to Exchange 2016 or Exchange 2019 to get better performance and support.
According to the information,the problem may be resulted from the http redirection in IIS was not configured or lost the configuration.
Please open IIS manager on the new server and locate Default Web Site-->owa.
If you don't want to disable HTTP connections and would like to redirect them to HTTPs connections as you mentioned in the post,please follow these steps:
- Select SSL Settings and uncheck Require SSL,click apply.
- Select HTTP redirect and fill in the blank "Redirect requests to this destination" with "https:\webmail.abc.com" ,click apply.
- Then restart IIS service to see if it acts as you expect.
Here is a document for your reference: Configure http to https redirection for Outlook on the web in Exchange Server
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