When you "double-click" an EXE file, your computer automatically executes these instructions designed by a software developer (eg. Symantec Brightmail[tm] Message Filter) on your PC.Every software application on your PC uses an executable file - your web browser, word processor, spreadsheet program, etc.For both internal and external SMTP relay scenarios the Frontend Transport service will be handling the connections.So whether you've deployed multi-role or CAS-only servers we'll only be referring to the Client Access server role from now.
Although the default Frontend Transport receive connector allows internal SMTP relay it will not allow external SMTP relay.Select the server that you wish to create the receive connector on. Exchange names the various default connectors using a standard of “Purpose SERVERNAME”, for example “Client Frontend E15MB1”. If the server you chose is multi-role you'll need to select the Frontend Transport role.Remember, the server should be either a multi-role server or a Client Access server. If the server is CAS-only then Frontend Transport will already be selected. For servers with a single network adapter the default binding will usually be fine.The Client Access server role is configured with a receive connector called “Default Frontend SERVERNAME” that is intended to be the internet-facing receive connector, so is already set up to receive SMTP connections from unauthenticated sources and allow them to send email to internal recipients.220 E15MB1.exchange2013Microsoft ESMTP MAIL Service ready at Mon, 1000 helo 250 E15MB1.exchange2013Hello [192.168.0.181] mail from: [email protected] 2.1.0 Sender OK rcpt to: [email protected] 2.1.5 Recipient OK data 354 Start mail input; end with . 250 2.6.0 <[email protected]> [In ternal Id=19911468384257] Queued mail for delivery This means that the only additional (and optional) step for making internal SMTP relay available to your applications and devices is to provide a DNS name for them to connect to.