@alexhaydock @neil @JustineSmithies If your IP range isn't on any blacklists, and you set it up properly, you should be fine. E.g. set up SPF, DMARC, DKIM, PTR records - and for dual stack ipv6/v4, that last part is critical; a&a lets you set the PTR record on your IPs, so you can make it match for both v4 and v6.
Some mail servers do whitelist mail server IPs, but that practise is rare. In general, I've not had issues sending mail to anyone, and I even run my business email on this connection.