I have created an email server that is capable of handling mail for multiple websites. e.g. [email protected], [email protected] etc. The emails are sending and receiving fine, but the spam score is terrible.
All of the websites hosted have MX records pointing to mail1.mysite.com. I have DKIM setup for mysite.com and spf setup too. Emails sent from mysite.com get a perfect spam free score, but those sent from other domains get sent straight to spam.
Is there a way for me to apply DKIM, reverse dns and SPF to domains that are using my mail1.mysite.com without having to loginto their DNS records and modify them?
No. The DKIM and SPF records must be added to the domain's DNS records by the domain owner or their authorized agent using the domain's authoritative name server.