Exchange mail flow guides › Inbound: POP3 and IMAP retrieval
Does Exchange Server have a built-in POP3 connector?
No. Exchange Server 2013, 2016, 2019 and Exchange Server SE include a POP3 service that lets clients read Exchange mailboxes over POP3, but no connector that fetches mail from external POP3 or IMAP mailboxes into Exchange. That function existed only in Windows Small Business Server, whose 2008 and 2011 editions shipped a POP3 Connector in the SBS console; the last version to include it was SBS 2011. On a standalone Exchange server the job is done by a separate connector service that downloads the provider mailboxes and hands the messages to Exchange over SMTP.
Updated on 2026-09-11
Two different things are called “POP3” in Exchange
The confusion comes from one word covering two opposite directions of mail flow. When an administrator searches for “Exchange POP3”, Microsoft Learn answers with the POP3 service. When the same administrator asks “how do I get the mail from our provider mailboxes into Exchange”, the answer is a connector, and Exchange does not have one.
| Exchange POP3 / IMAP4 service | POP3 connector | |
|---|---|---|
| Direction | Out of Exchange: a client reads an Exchange mailbox | Into Exchange: provider mailboxes are downloaded and delivered to Exchange users |
| Who connects to whom | Outlook, a phone or another mail program connects to the Exchange server on port 110 or 995 | The connector connects to the provider’s POP3 or IMAP server, then submits to Exchange over SMTP |
| Where it is configured | Exchange services Microsoft Exchange POP3 and POP3 Backend, external FQDN, port and TLS settings; disabled by default | Its own console: one entry per provider mailbox with server, login, protocol, schedule and the Exchange recipient(s) |
| Included in Exchange 2013, 2016, 2019, SE | Yes | No |
| Included in Windows SBS 2008 / 2011 | Yes (Exchange 2007 / 2010 inside SBS) | Yes, the SBS POP3 Connector |
What the Exchange POP3 service actually does
Microsoft describes POP3 and IMAP4 in Exchange Server as client-access protocols: users normally reach their mailboxes with Outlook (MAPI), Outlook on the web or Exchange ActiveSync, and POP3/IMAP4 are kept for clients that still rely on them. The services are not started by default. To use them you start Microsoft Exchange POP3 and Microsoft Exchange POP3 Backend, set them to automatic, configure the external server name, port and encryption method, and restart the services (see Microsoft Learn: POP3 and IMAP4 in Exchange Server and Enable and configure POP3 on an Exchange server). Exchange listens on port 995 for TLS-encrypted connections and on port 110 for unencrypted or STARTTLS connections. Microsoft also notes that POP3 and IMAP4 functionality in Exchange 2016 and 2019 is basically unchanged from Exchange 2013.
Nothing in that feature reaches out to another server. Enabling the POP3 service on Exchange therefore does not help with mail that sits in a mailbox at your Internet provider; it only lets a POP3 client pull mail out of Exchange.
Where the “built-in connector” memory comes from: Small Business Server
Windows Small Business Server bundled Exchange with a component that standalone Exchange never had. Microsoft’s documentation for the Windows SBS 2008 POP3 Connector describes it precisely: it retrieves e-mail from an external POP3 mailbox account and delivers it to the Exchange mailbox of a specified SBS user or distribution group, it can connect over SSL, it supports Basic, SPA and APOP authentication, and it has a Scheduling tab for the retrieval interval. Many small companies ran their whole inbound mail this way for a decade: the domain stayed at the provider, one POP3 mailbox per user or one catch-all mailbox for the domain, and the SBS connector emptied them into Exchange.
When those companies moved from SBS 2011 to Exchange 2013, 2016 or 2019 on a regular Windows Server, the POP3 Connector did not come along. It was an SBS console feature, not an Exchange feature, so a migrated Exchange organisation ends up with the POP3 service described above and no way to collect provider mailboxes. That is the moment the question in this guide’s title gets typed into a search box.
What you use instead on Exchange 2013 to SE
The replacement is a POP3/IMAP connector that runs as a Windows service next to (or on) the Exchange server. POPcon is a Windows service that downloads mail from POP3 and IMAP mailboxes into Microsoft Exchange Server and distributes it to the right mailboxes. It works the way the SBS connector worked, with the parts SBS shops usually missed:
- Standard SMTP delivery. POPcon submits each message to Exchange over SMTP through a receive connector, exactly as any other SMTP sender would. It does not use Exchange-specific APIs, which is why one connector covers Exchange 5.5 through 2019 and Exchange Server SE, all SBS versions, and other SMTP servers such as Lotus Domino/Notes and Tobit David (see which Exchange versions POPcon works with and the system requirements).
- Catch-all mailboxes as well as one mailbox per user. For a single domain mailbox POPcon reads the To:, CC:, X-Envelope-To, Delivered-To and related headers to find the real recipient and delivers each message to that Exchange mailbox, with catch-all rules for anything that does not match.
- POP3 and IMAP, with or without TLS, and OAuth 2.0 (modern authentication) for Microsoft 365 and Gmail mailboxes, so the connector keeps working after providers switch off password-only logins.
- Any number of provider accounts from one installation, each with its own protocol, credentials, retrieval interval and distribution rules.
- Runs on Windows Server 2012 to 2025 and Windows 7 to 11, on the Exchange server itself or on a separate machine.
On the Exchange side the only preparation is a receive connector that accepts SMTP connections from the connector’s IP address; the step-by-step is in Configuring Exchange 2013 / 2016 to receive mail from POPcon, with older guides for Exchange 2010 and SBS 2011 and Exchange 2007 and SBS 2008. Read more about POPcon or download the free trial and point it at one provider mailbox to see the flow end to end.
When you do not need a connector
A POP3 connector solves one specific situation: mail for your users arrives in mailboxes at a provider, and Exchange has to go and get it. If your domain’s MX record points at your Exchange server, at a mail gateway in front of it, or at a hosted filtering service that relays to Exchange, inbound mail is already delivered by SMTP and a connector adds nothing. Companies usually keep collecting by POP3 for a transition period (the old provider mailboxes still receive mail for a while, or some addresses cannot be moved yet) and then switch the MX record once every address lives on Exchange. Both setups can run at the same time on the same server: SMTP for the domains whose MX points at Exchange, the connector for the mailboxes that remain at the provider.
Frequently asked questions
Is the Exchange POP3 service the same thing as a POP3 connector?
No. The POP3 service lets a mail client such as Outlook or a phone read an Exchange mailbox over POP3; mail flows out of Exchange to the client. A POP3 connector logs in to an external POP3 or IMAP mailbox at your provider, downloads the messages and delivers them into Exchange; mail flows into Exchange. Exchange Server includes the first and has never included the second.
Did Exchange 2013 or Exchange 2016 have a POP3 connector?
No. Microsoft documents POP3 and IMAP4 in Exchange 2013, 2016, 2019 and Exchange Server SE as client-access protocols only. The POP3 Connector was a component of Windows Small Business Server, not of Exchange Server, and it was never offered for the standalone Exchange editions.
Can I keep using the SBS POP3 Connector after migrating to a newer Exchange?
No. The POP3 Connector is part of the Small Business Server console and runs only on the SBS machine. Once the SBS server is retired, the function has to be provided by a separate connector service that runs as a Windows service and submits the downloaded mail to the new Exchange server over SMTP.
Do I need a POP3 connector at all if my MX record already points at Exchange?
No. If the MX record for your domain points at your Exchange server (or at a gateway in front of it), inbound mail is delivered by SMTP and there is nothing to collect. A POP3 connector is only needed for mail that lands in provider mailboxes first: an ISP mailbox, a domain hosted at IONOS, Strato or GMX, a Gmail or Microsoft 365 mailbox, or addresses you cannot yet move to your own MX record.
More on inbound mail flow in the Exchange mail flow guides, or in the knowledge base. Auf Deutsch: Hat Exchange Server einen eingebauten POP3-Connector?