Mailflo provisions real Microsoft 365 Exchange Online mailboxes, configures SPF/DKIM/DMARC, runs Outlook warmup, and monitors SNDS & Defender signals — so your cold outreach lands in primary, every send.
Microsoft's sending environment is more complex than it looks. These are the four problems that kill M365 deliverability before the first campaign sends.
Microsoft 365's anti-spam engine (Defender) is aggressive with fresh sending accounts. Without a structured warmup calibrated to Defender's behavioral thresholds, new Exchange mailboxes get throttled or junked before any reputation is established.
Microsoft 365 reputation builds more slowly than Google Workspace. Pushing volume too fast triggers Defender's bulk-sending detection and can result in account suspension — a harder recovery than Gmail's equivalent.
Microsoft 365's DKIM requires CNAME selectors set up in DNS and activation through the Exchange admin center. A missing or broken selector breaks authentication silently — no bounce, no error, just filtered mail.
Unlike Google Postmaster Tools, Microsoft's SNDS reports at the IP level — not the domain level. Teams flying blind on M365 don't detect reputation problems until reply rates have already collapsed.
Six service layers that turn Microsoft 365 into a high-deliverability cold email engine — done for you, monitored continuously.
Real Exchange Online mailboxes provisioned under your Microsoft tenancy — with Outlook profiles, signatures, and correct SMTP/IMAP configuration — within one hour.
Full M365-specific authentication stack: Exchange Online SPF include, DKIM selectors generated and activated through Exchange admin, and a DMARC policy that meets Microsoft's bulk sender requirements — for every sending domain.
AI-driven warmup calibrated specifically for Microsoft Defender. Volume ramps over 21–28 days — slower than Gmail, tuned to Defender's behavioral thresholds — using a network of real Microsoft and Google inboxes.
Sending volume is distributed across all M365 mailboxes automatically, based on real-time health scores — keeping each Exchange account well below Microsoft's bulk-sending trigger thresholds at any scale.
Continuous monitoring of Microsoft SNDS IP data and Defender reputation signals, with instant alerts when any indicator drops — before the impact reaches your campaign inbox rates.
Blacklist checks across 50+ providers, inbox placement tests across Microsoft and Google networks, weekly performance reports, and same-day removal requests if any domain gets flagged.
Mailflo handles every step of your Microsoft 365 cold email setup — so your team skips straight to conversations.
Exchange Online accounts are set up under your Microsoft tenancy, with correct Outlook profiles, signatures, and SMTP/IMAP configuration — ready within one hour.
SPF, DKIM (via Exchange selectors), and DMARC records are published and validated for every sending domain. Microsoft SNDS baseline is established.
Every inbox enters our AI warmup network with Defender-calibrated pacing. Outlook reputation builds over 21–28 days while you prepare your sequences.
Inbox rotation keeps every mailbox below Defender's bulk-sending thresholds. SNDS and Defender monitoring catch any signal drop before campaigns are affected.
"We run a mixed M365 and Google Workspace stack through Mailflo. Our Outlook-heavy enterprise list went from 54% inbox placement to 91% in four weeks. The Defender-calibrated warmup made all the difference."
Microsoft 365 infrastructure is one layer. Mailflo covers the full stack.
Provision Gmail inboxes, configure Google-specific authentication, and monitor Google Postmaster — the highest-trust sending environment for cold outreach.
Explore GWS SetupEnd-to-end cold email infrastructure — secondary domains, DNS automation, inbox provisioning across both Google and Microsoft providers, warmup, and monitoring.
Explore InfrastructureStruggling with spam folder placement? Our deliverability audit and recovery service diagnoses authentication issues, blacklist damage, and sender reputation problems.
Explore DeliverabilityEverything teams ask before setting up Microsoft 365 for cold email.
Walk us through your sending volume and prospect profile. We'll scope the right M365 setup and have it running in days.
Exchange Online mailboxes provisioned, authenticated, warmed, and monitored — so Defender never stops your campaigns.