Gmail, Yahoo and Microsoft (Outlook.com, Hotmail and Live.com) have strict requirements for senders of large volumes. Email that doesn't meet them goes to spam or is rejected. Symplify supports all of the requirements, but some of them need setup on your side. This article explains what each provider requires and what you need to do.
- Requirements at a glance
- Authenticate your sender domain
- One-click unsubscribe
- Keep spam complaints low
Requirements at a glance
- SPF and DKIM: required by Gmail, Yahoo and Microsoft. You publish the DNS records, and Symplify signs your email.
- DMARC, at least p=none and aligned with your From domain: required by Gmail, Yahoo and Microsoft. You publish a DNS record.
- One-click unsubscribe: required by Gmail and Yahoo, recommended by Microsoft. Symplify adds it to every email.
- Unsubscribes processed within 2 days: required by Gmail and Yahoo, recommended by Microsoft. Symplify processes them right away.
- A visible unsubscribe link in the email: required by Gmail and Yahoo, recommended by Microsoft. You add it to your template.
- A spam complaint rate below 0.3%: required by Gmail and Yahoo, recommended by Microsoft. You keep it low through list quality.
Gmail and Microsoft apply the strictest rules to domains that send more than 5,000 emails a day to their users. Yahoo doesn't publish a volume limit. Set everything up regardless of your volume.
Note: Since May 2025, Microsoft rejects email from high-volume domains that fail these checks. The bounce message reads 550; 5.7.515 Access denied, sending domain ... does not meet the required authentication level.
Authenticate your sender domain
Symplify signs your email with a 2048-bit DKIM key, using the selector dkim2048. For the signature to count as your own, publish the key in your domain's DNS:
- Create the subdomain dkim2048._domainkey.<yourdomain.com>.
- Add a TXT record to this subdomain with the following value:
v=DKIM1; k=rsa; p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAzWGGBpzaOp4gCZ9o1f8PU8LOAlis2eTWQPWNLLuQ9urpC3oFp2i9kzkuFl5jMZY+3P4IEQJX+ju02khakL2rxe13E/FemB/OLqkhNkL+0dv8txBwIyK51FSI7ZJr96jiP3QwuyjOf8Xl9qAWOL9WFXqR+makG0u69hBO+V/dCzlprfH8M/2HGKp4HqtrqRvpdhSXTLz/dQG82Sz6xWClaT415PljmuDH2X7meHwPHuB6Lt36qmqAnBbgyMvyWOtB6eEIoxwqleYlDzqK/QmIpXL0k3e7JAZh6vwnrYTlzDDjFD/6wkeZZVptynwrOoO01H5A1KXg6n3+AkBlzHe0jwIDAQAB
Note: If your domain still only has the older 1024-bit key (k5._domainkey), Symplify uses that key until you add dkim2048. If neither key is published, Symplify signs with its own domain. That signature doesn't align with your From domain, so it doesn't count towards DMARC.
Also add the SPF record and a DMARC record. If you don't have a DMARC record yet, add at least this TXT record on _dmarc.<yourdomain.com>. Replace dmarc_reports@yourdomain.com with an existing address on your domain:
v=DMARC1; p=none; rua=mailto:dmarc_reports@yourdomain.com
For the SPF record and step-by-step instructions, see Sender domain authentication. That article also explains what to do if your DNS provider limits TXT records to 255 characters.
To have your setup verified, email domainsetup@symplify.com.
One-click unsubscribe
Every email sent from Symplify includes a one-click unsubscribe header. Gmail and other providers use it to show an Unsubscribe link next to the sender name, so contacts can unsubscribe without opening your email.
Symplify processes the unsubscribe right away, well within the 2 days the providers allow. The contact's email subscription is updated on their contact profile:
The header doesn't replace the unsubscribe link in your email. Keep a clearly visible unsubscribe link in your template. See Unsubscribe methods.
Keep spam complaints low
Gmail and Yahoo expect your spam complaint rate to stay below 0.3%. Both calculate it from email delivered to the inbox, so aim well below that. You can follow your rate for Gmail in Google Postmaster Tools.
The best way to keep complaints low is to send email that your contacts want. Symplify reports bounces and complaints and stops sending to addresses that bounce. Use the Engagement filter to stop sending to contacts who no longer open your email. See also Healthy lists and permission.