SPF and DKIM are necessities in order to improve your email reputation and deliverability.

But now it is not enough. DMARC has become in new standard for Emails.

To generate a DMARC, just visit the below link :

https://mxtoolbox.com/DMARCRecordGenerator.aspx

Once your DMARC record is generated, go to your DNS manager and create a TXT with Host/Name: _DMARC