Mail from several email accounts ending up in spam

Be informed that we have configured Sendgrid SMTP relay server, configured SPF and DKIM records, adhered to all anti-spam regulations, but still our few mail accounts mails (created in cpanel) are ending up in spam. About 4 of our mail accounts are working fine. The mails sent through them reach inbox but other 5 accounts mails are ending up in spam. How is this possible ?