How reputable UK and EU IPs get your mail delivered

The core value of a smarthost is not filtering — it's borrowed reputation. MxGuard relays your outbound mail from clean, well-established UK and EU IP addresses that already have sending reputation with the major mailbox providers.

Why that fixes deliverability. The big receivers — Gmail, Microsoft, Yahoo — decide inbox-vs-spam largely on the reputation of the sending IP. A self-hosted server on a residential, shared-hosting or NAT-pool IP starts from low trust no matter how legitimate its mail is. When MxGuard sends on your behalf from IPs that have a long, clean track record, the receiving side trusts the connection and delivers to the inbox.

The same IPs used for scanned inbound mail. These are the established addresses MxGuard already uses to deliver filtered inbound mail, so they carry genuine, maintained reputation rather than being a fresh, unproven pool.

Combined with the required SPF include, this is what turns silently spam-foldered or outright-rejected mail into delivered mail.