Adding DKIM Records in IONOS: DNS Setup Guide

This guide is part of our Setup & Configuration resources.

IONOS (formerly 1&1) is one of Europe's largest hosting providers, serving millions of domains worldwide. If your domain is registered or hosted with IONOS, adding a DKIM record is straightforward once you know where to look. This guide walks you through the entire process, from generating your DKIM keys to verifying that everything works. For background on DKIM and why it matters, see our complete DKIM guide.

What You Need Before Starting

Before you open the IONOS Control Panel, make sure you have two things ready:

Your DKIM public key record - the TXT value you will paste into DNS
Your selector name - the label that identifies your key (for example, default, mail, or a name provided by your email service). Need help? See how to find your DKIM selector

If you do not have a DKIM key pair yet, generate one with DKIM Creator. It runs entirely in your browser, so nothing is stored on a server.

Generate your DKIM keys first

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Generate DKIM Keys

IONOS Email vs. Third-Party Email

IONOS offers its own email service bundled with many hosting plans. How you set up DKIM depends on which email service you use.

Scenario	What to Do
IONOS Mail (built-in)	DKIM is handled automatically by IONOS. Check your email settings to confirm it is enabled.
Google Workspace	Add the DKIM TXT record Google provides to your IONOS DNS.
Microsoft 365	Add the CNAME records Microsoft provides to your IONOS DNS.
Mailchimp, SendGrid, etc.	Add the TXT or CNAME records your provider gives you to IONOS DNS.
Self-hosted mail server	Generate your own keys with DKIM Creator and add the TXT record to IONOS DNS.

If you use IONOS's own email, DKIM may already be active. Log in, go to Email in the Control Panel, and check your domain's authentication settings. For every other scenario, follow the steps below to add records manually.

Adding a DKIM TXT Record in IONOS

Log in to the IONOS Control Panel

Go to ionos.com and sign in with your IONOS account credentials. You will land on the main Control Panel dashboard.

Open Domains & SSL

In the left-hand menu, click Domains & SSL. This shows a list of all domains linked to your account.

Select your domain

Find the domain you want to add DKIM to and click on it. This opens the domain management page for that specific domain.

Go to DNS settings

Click the DNS tab. You will see a table of existing DNS records for your domain, including any A, MX, CNAME, and TXT records already in place.

Add a new TXT record

Click the Add Record button, then select TXT as the record type. IONOS will display a form with three fields:

Host Name - Enter your selector followed by ._domainkey. For example, if your selector is mail, type mail._domainkey.
Value - Paste the full DKIM record value. It starts with v=DKIM1; and includes your public key.
TTL - Leave this at the default (typically 1 hour) unless you have a reason to change it.

Save the record

Click Save. IONOS will add the TXT record to your domain's DNS zone. The record should appear in the DNS table within a few seconds.

Double-check the Host Name field carefully. A common mistake is forgetting the ._domainkey suffix. The full hostname should be selector._domainkey, not just the selector name on its own.

What Your DNS Record Should Look Like

After saving, your new record should appear in the IONOS DNS table with values similar to these:

Field	Example Value
Type	TXT
Host Name	`mail._domainkey`
Value	`v=DKIM1; k=rsa; p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8A...`
TTL	1 Hour (3600)

IONOS automatically appends your domain name to the host. So if you enter mail._domainkey, the full DNS name becomes mail._domainkey.yourdomain.com. You do not need to type the domain yourself.

Adding CNAME Records Instead of TXT

Some email providers (like Microsoft 365) use CNAME records for DKIM instead of TXT records. The process in IONOS is nearly identical:

Go to DNS settings for your domain
Click Add Record and choose CNAME
Enter the hostname your provider specified (e.g., selector1._domainkey)
Enter the target value your provider gave you
Save the record

Check your email provider's documentation to confirm whether they require TXT or CNAME records. For a deeper comparison, see DKIM TXT vs CNAME records.

Verifying Your DKIM Record

DNS changes in IONOS usually take effect within an hour, though full propagation across the internet can take up to 48 hours. Once you have waited at least an hour, verify that your record is live.

Check the DNS record

Use a DNS lookup tool or run this command in a terminal:

dig TXT mail._domainkey.yourdomain.com +short

Replace mail with your selector and yourdomain.com with your actual domain. You should see your DKIM record value in the response.

Send a test email

Send an email from the account that uses DKIM to a Gmail address. Open the message in Gmail, click the three-dot menu, and select Show original. Look for dkim=pass in the Authentication-Results header.

Troubleshoot if needed

If the lookup returns nothing, give it more time or double-check the hostname and value in your IONOS DNS settings. Make sure there are no extra spaces or missing characters in the record value.

Common Issues with IONOS DKIM Setup

Record not found after saving - DNS propagation is not instant. Wait at least one hour before testing. If the record still does not appear after 24 hours, log back in to IONOS and confirm it was saved correctly.

Long TXT record gets truncated - 2048-bit DKIM keys produce long values. IONOS supports long TXT records, but if you run into issues, make sure you are pasting the entire value without line breaks. Some providers require the value to be split into 255-character strings enclosed in quotes, but IONOS typically handles this automatically. See DKIM record too long for more solutions.

Wrong hostname format - Remember that IONOS appends your domain automatically. Enter only selector._domainkey, not selector._domainkey.yourdomain.com. Adding the full domain will result in a doubled hostname like selector._domainkey.yourdomain.com.yourdomain.com.

DKIM failing despite correct DNS - Make sure your mail server or email provider is actually signing outgoing messages with the matching private key. The DNS record alone does not enable signing - it only publishes the public key for verification.

Key size recommendation

Use 2048-bit keys for stronger security. IONOS supports the longer TXT record values that 2048-bit keys require, so there is no reason to use 1024-bit keys unless another provider in your setup has a length limitation.

Next Steps After Adding DKIM

Once your DKIM record is live and verified, consider completing your email authentication setup:

SPF - Authorize which servers can send email for your domain
DMARC - Set a policy that tells receiving servers how to handle emails that fail DKIM or SPF checks
Key rotation - Plan to rotate your DKIM keys periodically (once a year is a common schedule)

References

RFC 6376 — DomainKeys Identified Mail (DKIM) Signatures
RFC 1035 — Domain Names — Implementation and Specification
IONOS — DNS management documentation

Ready to set up DKIM for your domain on IONOS? Start by generating your keys.

Generate DKIM keys for your domain

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