I've gotten DKIM, SPF, DMARC, etc all verified on my Digital Ocean droplet (and removed from various greylists) but still get spam checked by AT&T / SBC Global,

I've gotten DKIM, SPF, DMARC, etc all verified on my Digital Ocean droplet (and removed from various greylists) but still get spam checked by AT&T / SBC Global, who is the main offender of keeping a private list. I've been removed for now from their lists... but they tend to re-add IPs from previous ranges for no reason.