IONOS Mail works in any mail app that speaks IMAP. Incoming mail (IMAP): imap.ionos.com, port 993 (SSL/TLS). Outgoing mail (SMTP): smtp.ionos.com, port 465 (SSL/TLS). The user name is your full email address, and the password is the password of that email address (each IONOS address has its own). In LocalInbox, choose Other IMAP account and type these in under Server settings.
Server settings
| Server | Host name | Port | Security |
|---|---|---|---|
| Incoming (IMAP) | imap.ionos.com | 993 | SSL/TLS |
| Outgoing (SMTP) | smtp.ionos.com | 465 | SSL/TLS |
| Outgoing (SMTP), other port | smtp.ionos.com | 587 | STARTTLS |
| Incoming (POP3) | pop.ionos.com | 995 | SSL/TLS |
These are IONOS's servers in the US. In the UK they're imap.ionos.co.uk, smtp.ionos.co.uk and pop.ionos.co.uk, and in Germany imap.ionos.de, smtp.ionos.de and pop.ionos.de, on the same ports. Elsewhere, your country's IONOS help site lists them.
What the ports and security mean: IMAP ports and SMTP ports.
POP3 is for apps that use it. LocalInbox uses IMAP, so read, moved and deleted mail stays the same on every device: POP3 and IMAP compared.
Steps
- In LocalInbox, open Settings › Accounts and click Add Account (or use the welcome screen the first time).
- Choose Other IMAP account. Enter your IONOS address, and the password of that email address (each IONOS address has its own) as the password.
- Open Server settings. Under Incoming mail (IMAP), enter imap.ionos.com and port 993, and choose TLS.
- Under Outgoing mail (SMTP), enter smtp.ionos.com and port 465, and choose TLS.
- Leave User name empty, and LocalInbox signs in with your full address, which is what IONOS expects.
- Click Connect. LocalInbox signs in and starts syncing your mail.
Troubleshooting
LocalInbox says the password is wrong
LocalInbox needs the password of that email address (each IONOS address has its own). Copy it again, without spaces before or after.
LocalInbox says it can't connect
The message says what to fix: nothing answering at the port, the wrong kind of TLS for the port, an untrusted certificate, an unknown server name, or a timeout. Check what you typed under Server settings against the table at the top of this page.
Mail comes in, but sending fails
Some networks block port 465. IONOS also takes port 587 with STARTTLS: change it under Server settings › Outgoing mail (SMTP).
Sources
IONOS Mail's settings were checked against its own help pages in November 2026 and can change. The steps in LocalInbox come from the app.
Questions
What are the IONOS Mail IMAP and SMTP settings?
Incoming (IMAP): imap.ionos.com, port 993, SSL/TLS. Outgoing (SMTP): smtp.ionos.com, port 465, SSL/TLS. Outgoing (SMTP), other port: smtp.ionos.com, port 587, STARTTLS. These are IONOS's servers in the US. In the UK they're imap.ionos.co.uk, smtp.ionos.co.uk and pop.ionos.co.uk, and in Germany imap.ionos.de, smtp.ionos.de and pop.ionos.de, on the same ports. Elsewhere, your country's IONOS help site lists them.
Where does LocalInbox keep the password?
In the macOS Keychain on your Mac. It's never written to a file or sent anywhere except your mail server.
What are the IONOS Mail POP3 settings?
Incoming (POP3): pop.ionos.com, port 995, SSL/TLS, for apps that use POP3; outgoing mail goes through the same SMTP server as with IMAP. LocalInbox uses IMAP instead, which keeps read, moved and deleted mail the same in webmail, on your phone and on your Mac. POP3 downloads mail to one device.
Can I add IONOS Mail on iPhone or iPad?
Yes, the same way, in LocalInbox for iPhone and iPad: Settings › Accounts › Add Account, then Other IMAP account. Type in the same server settings and password. Already added it on your Mac? Add Account › From your Mac copies it with a QR code, password included. https://localinbox.app/iphone