Exchange-Online

Migrating a 107GB Gmail Mailbox with LAO: What Microsoft's Docs Don't Tell You

Migrating a single Accounts Payable mailbox from Google Workspace to Exchange Online should have been the easy part of a larger phased migration. It wasn’t. The mailbox was 100GB+ with 600,000+ items, which put it past Exchange Online’s standard migration path and into Large Archive Onboarding (LAO) territory. LAO is the only supported mechanism for migrating a mailbox this size from Gmail while splitting content between primary and archive by date or folder. ...

Chasing SPF temperror in Exchange Online: DNS Timeouts, Mimecast SRS, and Getting Microsoft Engineering Involved

The Problem Inbound mail was intermittently producing spf=temperror results in Exchange Online despite a valid, RFC 7208-compliant SPF record and no delivery failures. Messages were accepted and delivered, so no NDRs, no user-visible symptoms, but authentication headers showed this: Authentication-Results: spf=temperror (sender IP is 209.85.128.197) smtp.mailfrom=yourdomain.com Received-SPF: TempError (protection.outlook.com: error in processing during lookup of yourdomain.com: DNS Timeout) External resolvers (Google (8.8.8.8), Cloudflare (1.1.1.1)), direct queries to the authoritative nameserver, all resolved the SPF record cleanly and consistently. The timeout was happening exclusively inside Exchange Online’s MTA infrastructure. ...

What a Google Workspace to M365 Migration Actually Looks Like Mid-Flight

Most migration guides describe the happy path. This isn’t that. This is what you actually find when you inherit a migration in progress and start pulling on threads. The Setup Mid-flight GWS to M365 migration. Test batches already running. Domain setup incomplete. Multiple migration endpoints in Exchange Online pointing at a GCP service account that nobody can confirm ownership of. This is a fairly normal state for an org-scale migration that started before all the architecture decisions were locked in. ...