Email providers
Transactional and marketing ESPs — SPF include strings and DKIM records with DMARC alignment in mind.
SendGrid
SPF + DKIM guides
Mailgun
SPF + DKIM guides
Google Workspace
SPF + DKIM guides
Microsoft 365
SPF + DKIM guides
Postmark
SPF + DKIM guides
Amazon SES
SPF + DKIM guides
Mailchimp
SPF + DKIM guides
Klaviyo
SPF + DKIM guides
HubSpot
SPF + DKIM guides
Brevo
SPF + DKIM guides