Force Exchange 2010 to send email externally

Fresh Exchange 2010 setup sends internal mail fine but external mail sits in the queue or bounces. Internal to internal is perfect.

What piece of external sending is missing on a new install?

Internal working while external does not on a fresh install points at the send connector, the piece that carries mail off your organization to the internet, which a new Exchange does not create for you. The checklist:

1

Confirm the missing piece: Get-SendConnector in the Exchange Management Shell. A new install often returns nothing, no send connector meaning no route to the outside, which is precisely the internal fine external stuck symptom.

2

Create the send connector: in the Exchange Management Console, Organization Configuration, Hub Transport, Send Connectors, New, an Internet type connector with address space * for all external domains. Choose delivery, either DNS routing where Exchange resolves recipients directly or a smart host relaying through your ISP or a mail provider, smart host being common where the ISP blocks direct port 25 or your IP lacks reverse DNS.

3

Fix the deliverability foundations DNS routing needs: a static IP with matching reverse DNS PTR record, an SPF record authorizing your server and port 25 outbound open, the trio without which direct sending bounces or lands in spam. Smart host routing sidesteps these by handing delivery to a provider who has them, the pragmatic choice for many small setups.

4

Test end to end: send to an external address and watch the queue, Get-Queue showing whether mail leaves. A message that sends and arrives with a clean SPF pass confirms the connector plus foundations, and a mail tester service reading your SPF, PTR and content score catches the spam folder problems a plain delivery test misses.

The choice between DNS and smart host routing deserves its honest framing: DNS routing is self reliant but demands the IP reputation groundwork, PTR, SPF and eventually DKIM and DMARC, that determines whether your mail reaches inboxes or spam folders, while smart host routing through a reputable provider inherits their deliverability, trading a dependency for reaching inboxes reliably, frequently the right call for organizations without a mail reputation to defend.

No send connector at all, exactly the empty Get-SendConnector. Created one with smart host routing through our ISP since our IP had no PTR record, and external mail flows and passes SPF. The DNS versus smart host framing made the choice obvious for our situation.