Email signature:
Less is more: limit the number of images, logos and links in your signature.
The fewer the better.
Optimize images: If you use images, make sure they are optimized (file size) and use alt attributes (descriptive text for the image).
Clear contact details: Make sure your contact details are complete and correct (name, title, phone number, email, company address).
No unnecessary information: Avoid superfluous legal information or long disclaimers.
Text version: Make sure that your signature is also easy to read in a text-only version.
Domain and e-mail settings:
Set up SPF (Sender Policy Framework): Make sure SPF is set up correctly for your domain. This helps to confirm that emails are actually being sent from your server.
Enable DKIM (DomainKeys Identified Mail): Enable DKIM to digitally sign your emails. This confirms that the email has not been altered in transit.
Configure DMARC (Domain-based Message Authentication, Reporting & Conformance): Configure DMARC to specify how email servers should handle emails that do not pass SPF and DKIM.
Check reverse DNS (PTR record): Ensure that your server has a valid reverse DNS record.
Monitor IP reputation: Regularly monitor the reputation of your IP address. A poor IP reputation can lead to your emails ending up in spam.
Email list maintenance: Keep your email lists clean and up to date. Remove inactive or invalid email addresses.
General tips:
Use mail testers: Use tools such as mail testers to check your emails for spam characteristics before you send them.
Send test emails: Send test emails to different email providers (Gmail, Outlook, etc.) to see how your emails are received there.
Get feedback: Ask recipients for feedback on whether your emails have ended up in spam.
Avoid spam words: Avoid words and phrases that are often used in spam emails (e.g. "free", "make money").
Check regularly: Check your settings regularly and adjust them if necessary.