Hi @Anil Kumar Singam ,
Can I configure exchange server to receive email from all external domains without edge transport server.
Yes. As mentioned by Manu, it's not mandatory to install Edge server role. The inbound mail flow with no Edge server is as follows:
Reference: Mail flow and the transport pipeline-Inbound mail flow (no Edge Transport servers)
By default, a Receive connector "Default Frontend <Mailbox server name>" to accept mail from the Internet is implicitly created upon installation of Exchange, and that would be enough to receive incoming messages as long as 1) the MX record is published properly, 2) port 25 is open for mail flow and 3) the accepted domain is added.
As regards to configure the MX record and open the port, you may refer to the relevant sections in the blog below for more information:
Configuring Public DNS and MX records for exchange 2013
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Regarding the accepted domain, by default, the FQDN of your forest root domain in AD is configured as an authoritative domain when installing the first mailbox server, but you can add other accepted domains as well. For more explanation about accepted domains, see Accepted domains in Exchange Server.
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