DKIM (DomainKeys Identified Mail) is a digital signature added to every email you send. DKIM proves to your customer's email provider that the email really came from your domain and wasn't changed on the way.
If you send WithWine emails from your own email address, setting up DKIM helps keep your receipts, invoices, club emails and newsletters out of spam folders. Setting up DKIM also helps stop Outlook showing an "Unverified" warning next to your winery's name.
What DKIM stands for and how DKIM works
DKIM stands for DomainKeys Identified Mail. DKIM works like a wax seal on a letter:
When WithWine sends an email from your address, WithWine adds a hidden signature to the email.
Your domain (for example [yourdomain]) publishes a matching key in the domain's DNS records.
The customer's email provider (Gmail, Outlook, Yahoo or Apple Mail) checks the signature against the key. If the signature and the key match, the provider knows the email is genuine and hasn't been changed.
The three email checks: SPF, DKIM and DMARC
Email providers use three checks to decide whether to trust an email:
SPF (Sender Policy Framework): a list, published on your domain, of the servers allowed to send email for your domain.
DKIM (DomainKeys Identified Mail): a signature on each email that proves the email came from your domain.
DMARC (Domain-based Message Authentication, Reporting and Conformance): a rule on your domain that tells email providers what to do with an email that fails the other checks: do nothing, send the email to spam, or reject the email. To pass DMARC, an email must pass SPF or DKIM for the same domain shown in the From address.
DKIM is the check that matters most for WithWine emails. WithWine sends emails on your behalf through WithWine's email service (Amazon Web Services). The DKIM signature is what links those emails to your domain.
Why emails go to spam
Gmail and Yahoo require every sender to pass SPF or DKIM. Senders of more than 5,000 emails a day must pass SPF and DKIM and have a DMARC record.
Since May 2025, Microsoft (Outlook.com, Hotmail and Live) has required SPF, DKIM and DMARC for senders of more than 5,000 emails a day. Email that doesn't meet the requirements goes to the Junk folder and can later be rejected.
Even at lower volumes, emails that can't be verified are more likely to land in spam or promotions folders.
Why Outlook shows "Unverified"
Outlook shows "Unverified", and a question mark instead of your logo or initials, when Outlook can't confirm the email really came from the sender in the From address. The email may be completely genuine, but customers are more likely to ignore the email, delete the email or report the email as junk.
Asking customers to add you to their safe senders list doesn't fix the cause. Setting up DKIM for your domain does.
Do I need DKIM if I leave the From Email Address blank?
No. If the From Email Address in Settings > My Brand > Brand Details is blank, WithWine sends your emails from WithWine's own address, contact@withwine.com. That address already passes SPF, DKIM and DMARC. The sender name shows as WithWine, and the email content is still from your winery.
Do I need DKIM if I set a From Email Address?
Yes. When you send from your own address (for example orders@[yourdomain]), each email has to prove the email is allowed to use your domain. Without DKIM records on your domain:
WithWine emails can't pass DMARC for your domain, and
if your domain already has a DMARC policy set to quarantine or reject (your IT provider or email host may have set one up without telling you), your WithWine emails can go to spam or be rejected.
Important: setting your own From Email Address without setting up DKIM can make delivery worse than leaving the From Email Address blank. Set up DKIM as soon as your From Email Address is verified.
Don't use a free email address as your From Email Address
Don't use a Gmail, Yahoo, Hotmail, Outlook.com or iCloud address as your From Email Address. You can't add DKIM records to those domains, so your emails can't be fully verified. Use an address on your own domain, such as hello@yourwinery.com.
Before you start setting up DKIM
A From Email Address on your own domain, verified in Settings > My Brand > Brand Details. Both Amazon Web Services Verified and WithWine Verified must show.
Access to the DNS settings for your domain. DNS settings are usually with the company you bought the domain from (such as GoDaddy, Crazy Domains, VentraIP or Namecheap), or the company that hosts your website or email. If you're not sure, ask whoever manages your website or IT.