IONOS SMTP settings: smtp.ionos.com (smtp.ionos.de), port 587
IONOS / 1&1 outgoing mail server: smtp.ionos.com (US/UK) or smtp.ionos.de (Germany), port 587 STARTTLS or 465 SSL, full mailbox address and password. Recipient limits and error fixes.
IONOS (1&1) outgoing mail server:
smtp.ionos.com, port <code>587</code> (STARTTLS) or <code>465</code> (SSL/TLS), username = the full mailbox address, password = the mailbox password set in the IONOS Email settings.
IONOS (1&1) SMTP settings at a glance
| Outgoing (SMTP) host | smtp.ionos.com (US, UK, CA) — smtp.ionos.de (DE), smtp.ionos.fr (FR), smtp.ionos.es (ES) |
|---|---|
| Ports & encryption |
587 — STARTTLS <em>(recommended)</em>465 — SSL/TLS |
| Username | the full mailbox address |
| Password | the mailbox password set in the IONOS Email settings |
| Authentication | Credentials are per mailbox; the host depends on the country your contract is in. |
How to set up IONOS (1&1) SMTP
- IONOS → Email → create/select the mailbox → set a password.
- App settings: host smtp.ionos.com (or your country host), port 587 STARTTLS, username = full address, password = mailbox password.
Sending limits
- IONOS limits mailboxes to about 500 recipients per day (higher on business plans) and blocks bulk mail; web servers cannot use port 25 outbound.
Things that catch people out
- Old 1&1 hosts (smtp.1and1.com, auth.smtp.1and1.co.uk) still resolve but should be replaced with the ionos hosts.
Common IONOS (1&1) SMTP errors
| Server reply | Meaning | Fix |
|---|---|---|
535 Authentication credentials invalid | Wrong country host or password. | Match the host to your contract country. |
More codes: 535 authentication failed, 550 relay denied, 554 rejected as spam, connection timed out — or all SMTP error codes.
When IONOS (1&1) is not enough for your app
When a provider caps you or blocks a port, point the same app at QueenSMTP instead: host smtp.queensmtp.com, port 587 (STARTTLS) or 465 (SSL), your SMTP username and password from the dashboard. $5/year plus $0.10 per 1,000 emails, 100 free a day to test.
Get SMTP credentials — free to test Test IONOS (1&1) nowRelated settings
IONOS (1&1) SMTP — questions
smtp.ionos.com (smtp.ionos.de for Germany) on port 587 with STARTTLS or 465 with SSL, with the full mailbox address and password.
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