Instantly, Smartlead and Lemlist Sending Infrastructure

The configuration that matters is under 30 sends per mailbox per day and a complaint rate under 0.10 percent in Google Postmaster Tools, a third of the 0.30 percent threshold Google set for bulk senders in February 2024. For most clients that arithmetic means twelve to twenty mailboxes across three to five secondary domains and a first send about four weeks after we start, not a higher daily limit on the domain you already own. Domains: Secondary domains only. Your corporate root never sends cold, because a complaint rate earned in outbound follows your invoices and your password resets. We register close variants, point a 301 at your main site so the domain resolves for anyone who checks, and let them age 21 to 28 days before the first cold send. Whether a domain needs a one-page site depends on who you are writing to, and we will tell you when it does not. DNS: SPF kept inside the ten-lookup limit, which is the single most common misconfiguration we inherit. DKIM at 2048 bits. DMARC opening at p=none with rua pointed at a mailbox somebody actually reads, moving to p=quarantine only after two clean weeks of reports. MTA-STS and TLS-RPT where the provider supports them. A custom tracking domain on a CNAME, which in our builds carries the unsubscribe link and nothing else, because open and click tracking are off by default and we will argue the point before switching them on. Mailbox choice: Google Workspace, Microsoft 365, or private SMTP infrastructure. We choose per client and tell you why. Microsoft tenants throttle on a different curve, and Outlook.com began enforcing SPF, DKIM and DMARC on high-volume senders in May 2025. If half your target domains carry Microsoft MX records, that decision is not cosmetic. Warmup: 21 to 35 days, ramping from two per day to thirty, with the warmup pool left running at reduced volume once campaigns start rather than switched off on launch day. We read domain reputation and spam rate in Postmaster Tools daily through the first three weeks and send you the screenshots, not a summary of them. Platform: Smartlead where there are sub-accounts and webhook-driven CRM writes. Instantly where one team wants a single Unibox and less to administer. Lemlist where the sequence genuinely needs LinkedIn and call steps in the same flow. We hold no affiliate or partner status with any of the three and take no vendor commission, which their public partner directories will confirm. Rules we set inside the platform: Sending windows in the recipient's timezone, weekdays only. Mailbox rotation with per-mailbox caps rather than one campaign-level number that quietly overloads whichever inbox is healthiest. Automatic pause at three percent bounce, which stops a bad import before it costs a domain. Suppression synced from the CRM by webhook rather than a monthly CSV. Reply routing to a master inbox with a named owner and an answer time measured in hours. CRM: A contact is created on positive reply only. Not on send, not on open. Pipelines that fill with sends stop being read inside a month, and then nobody notices the reply that mattered. Handover: A runbook with every DNS record as deployed, credentials in your password manager under your ownership, domains registered in your account rather than ours, and a monthly cost sheet covering seats, platform tier, enrichment credits and verification, so you can run this without us and end the engagement without losing it. What we refuse: We will not send from your primary domain. We will not add mailboxes to fix a reply-rate problem, which is a copy or list problem wearing an infrastructure costume. We do not buy aged domains whose history we cannot see. We do not remove unsubscribe links. We do not send to Canadian recipients without documented consent. Who this is not for: Teams who need six figures of monthly send volume. Anyone unwilling to wait four weeks for the first email. Anyone who wants the infrastructure held in an agency account so it cannot be moved.