Mailforge is the sending-infrastructure product in the Forge ecosystem, sitting alongside Salesforge, Infraforge, Warmforge and Primeforge. Its one job: spin up dozens or hundreds of cold email domains and mailboxes in minutes, instead of the days you would spend clicking through Google Workspace admin panels one tenant at a time. The mechanics are simple. You buy domains in bulk (a .com runs about $14 yearly), generate mailboxes on shared IP pools built specifically for outreach, and Mailforge writes the SPF, DKIM and DMARC records for you. Bulk DNS updates, workspaces, SSL and domain masking, and exports that drop mailboxes straight into Instantly, Smartlead, Salesforge or any sender. In a GTM stack it is the layer under your cold email tool. The sequencer decides who gets what message and when; Mailforge supplies the domains and inboxes that actually carry the volume, so you can spread sending thin, retire a burned domain, and stand up its replacement the same afternoon. We have not run Mailforge on our own campaigns, so no first-person verdict. But deliverability infrastructure is a real layer we build for clients, and Mailforge is a credible way to provision domains and mailboxes fast. We would weigh it against Zapmail and ScaledMail on price, IP quality, and how cleanly it feeds the sender you already run.