Setting up an IONOS email account on a third-party client requires manually entering server settings that auto-configuration does not always detect. IMAP or POP3, port 465 or 587, account password or customer area password: each combination yields a different result depending on the software used. This article compares the settings required by Outlook, Gmail, and Apple Mail to identify the friction points specific to each client.
IONOS IMAP and SMTP Settings: Comparison Table by Email Client
The majority of connection failures stem from confusion between two pairs of values: the SMTP port and the associated encryption protocol. IONOS accepts two distinct SMTP configurations, but not all clients handle both in the same way.
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| Parameter | Outlook (Windows/Mac) | Gmail (via “Check other accounts”) | Apple Mail (macOS/iOS) |
|---|---|---|---|
| Incoming server (IMAP) | imap.ionos.fr | imap.ionos.fr | imap.ionos.fr |
| IMAP port | 993 | 993 | 993 |
| Incoming encryption | SSL/TLS | SSL/TLS | SSL/TLS |
| Outgoing server (SMTP) | smtp.ionos.fr | smtp.ionos.fr | smtp.ionos.fr |
| SMTP port | 465 (SSL/TLS) or 587 (STARTTLS) | 587 (STARTTLS) | 465 (SSL/TLS) or 587 (STARTTLS) |
| SMTP authentication | Yes | Yes | Yes |
The incoming server remains the same for all three clients. The differences arise with the SMTP port and the type of encryption. Gmail requires port 587 with STARTTLS when adding an external account, while Outlook and Apple Mail allow the choice between 465 (SSL/TLS) and 587 (STARTTLS).
A guide detailing the IONOS IMAP and SMTP configuration on Geekovision includes these settings with screenshots for each step.
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IONOS Password: The Distinction That Blocks Connection
The most common trap is not technical; it is administrative. IONOS uses two distinct passwords: one for the customer area and one for the mailbox. The customer area password is used to access the administration panel. The mailbox password, set separately when creating the address, is the only one accepted by email clients.
Outlook displays an error “failed to connect to the server” without specifying the source. Apple Mail tries several combinations before requesting manual input. Gmail simply rejects the connection without an explicit message.
To verify or reset the mailbox password, you must go through the IONOS panel (under “Email”), select the relevant address, and change the password from that space. The new password takes effect within a few minutes, but sessions already open on other devices will be disconnected.
Outlook and IONOS: STARTTLS or SSL/TLS Depending on the Version
Recent versions of Outlook (Microsoft 365, Outlook for Windows “new”) offer automatic detection of server settings. This detection works correctly for Microsoft accounts but regularly fails with IONOS. The software then switches to manual mode.
In manual configuration, Outlook asks you to choose between IMAP and POP3. IMAP synchronizes folders across all devices, whereas POP3 downloads messages locally and removes them from the server (unless set otherwise). For multi-device use, IMAP is the only coherent choice.
- Enter imap.ionos.fr on port 993 with SSL/TLS for the incoming server
- Enter smtp.ionos.fr on port 465 with SSL/TLS (or 587 with STARTTLS) for the outgoing server
- Enable SMTP authentication with the same credentials as the incoming server
- Use the full email address as the username (not just the part before the at sign)
On Outlook for Mac, the “username” field is sometimes hidden. You need to click on “Advanced settings” to access it and enter the full address.
Common Error on Port 587
Some users configure port 587 by selecting SSL/TLS instead of STARTTLS. The result: the connection is established but no message is sent. Port 587 works exclusively with STARTTLS at IONOS. Conversely, port 465 requires SSL/TLS. Mixing the two causes a silent blockage.
Gmail: Adding an IONOS Account for Sending and Receiving
Gmail allows you to retrieve messages from an IONOS account via the “Check other email accounts” function in the settings. This method uses POP3 by default for receiving, which may surprise users accustomed to IMAP.
For sending, Gmail offers to add a custom sender address. It is at this stage that the SMTP settings come into play. Gmail requires port 587 with STARTTLS for the outgoing server. Port 465 is not offered in the interface.
Folder synchronization remains limited: Gmail does not replicate the IMAP structure of the IONOS account. Retrieved messages arrive in the Gmail inbox, mixed with others. Creating a Gmail filter to automatically label messages from the IONOS address helps maintain visual separation.
Apple Mail and IONOS: The Specific Password as a Prerequisite
Apple Mail (macOS and iOS) automatically detects certain providers when adding an account. IONOS does not appear in this automatic detection list. The software therefore requests manual input after an initial connection failure.
On iOS, the sequence is as follows: Settings, Mail, Accounts, Add Account, Other. The user enters the IONOS address, the mailbox password (not the customer area password), then accesses the incoming and outgoing server fields.
- Incoming server: imap.ionos.fr, port 993, SSL enabled
- Outgoing server: smtp.ionos.fr, port 465 with SSL or 587 with STARTTLS
- Username: the full email address for both servers
On macOS, Apple Mail may display a warning “Cannot verify the identity of the server” during the first connection. Accepting the certificate allows you to proceed without compromising encryption security.
The common point among the three clients remains the same: SMTP authentication must be enabled with the mailbox credentials. Without this activation, incoming messages arrive normally, but each sending attempt fails. This is the first check to perform when receiving works but sending does not.