If list quality is one side of deliverability, authentication is another.
SPF, DKIM, and DMARC help receiving systems understand whether the email coming from your domain should be trusted.
SPF
SPF helps define which sending systems are allowed to send on behalf of your domain.
DKIM
DKIM adds a cryptographic signature that helps prove the message was sent by an authorized system and was not altered in transit.
DMARC
DMARC tells receiving systems how to handle mail that fails SPF or DKIM alignment and gives you reporting visibility.
Why this matters alongside list cleaning
You can have a cleaner list and still underperform if your domain authentication is weak. These are different layers of the same broader deliverability picture.
A practical approach
Set up SPF, DKIM, and DMARC based on your sending provider’s documentation, then keep list hygiene strong on the data side.
That combination is more powerful than focusing on only one half of the problem.
Where MailCull fits
MailCull helps on the data-quality side of the equation by giving you a better send file.
Authentication helps on the domain-trust side.
You want both.
Clean the list in MailCull before the next authenticated send →