I'm new to managing my own Ubuntu VPS for business and recently set up Postfix to send emails. I tested sending emails to multiple Outlook addresses, but they all landed in the junk folder. When I looked at the email headers, everything passed except DKIM. I've registered a domain with Hostinger and have configured all my DNS settings, including DKIM, SPF, and DMARC. DKIM validators say everything's good, but for some reason, Outlook fails all DKIM checks. I'm really puzzled about why this is happening.
5 Answers
Have you confirmed that Postfix is actually set up to sign your emails with DKIM? That's a common oversight!
To really help you out, sharing your domain name would be useful. Then we could check the SPF and DKIM records for any mistakes. Also, it's possible that the IP address of your VPS might be on a spam list, which can block you from sending emails successfully. Without that info, it's tough to analyze your issue further.
It sounds like you're on the right track, but remember that having the DKIM record in your DNS is just one part of the equation. Postfix needs to actually sign your emails with the DKIM private key for it to work. DKIM is all about attaching a signature that proves the email is from you, while the public key helps verify that signature. Also, keep an eye on your SPF records—those help specify which IPs can send on behalf of your domain. Make sure they're set up correctly!
Thank you, that’s so helpful!
Learndmarc.com has some great online instructions that could guide you through.
If you want to visualize the whole DKIM and DMARC process, check out learndmarc.com. They have some handy tools.
Before anything else, you should look into what tool you're using to add DKIM to your messages. Postfix usually doesn't handle DKIM signing by itself; it typically needs to work with an additional tool. When I set up my relay, it took a lot of tweaking. Pay attention to the logs to spot any issues—they can provide a ton of insight into what's wrong.
Yes, I did set it up.