Corporate email is sometimes treated as 'open a cPanel account and done'. A choice made without measuring delivery reputation, continuity and retention requirements can lead to spam placement, access issues or business-loss risk. The decision should cover not only price but also reputation, backup, mobile access and legal-retention requirements.
Scenarios where M365 wins
- The team lives in Outlook + Teams + OneDrive
- Consistent mobile push and calendar sharing are critical
- Legal hold / eDiscovery is required
- IT is small and does not want to babysit Postfix
When self-hosted still makes sense
A self-hosted option may be considered for one-way notification mailboxes, dedicated SMTP for high-volume transactional mail, or some SMB scopes where per-seat licensing is not a good fit. Validate SPF, DKIM, DMARC, reverse DNS, abuse controls and a sending warm-up plan; measure delivery reputation by provider, recipient network and sending behaviour.
Hybrid: forward + keep
In some scopes, user mailboxes remain on M365 while selected service addresses use a separate mail flow. Forward-and-keep is not a backup by itself; test delivery loops, unauthorised duplication, retention, search, deletion and cross-border-transfer implications. Design archival or backup needs through a separate policy and restore testing.
The wrong choice is not 'cheap hosting mail' — it is an unmeasured choice. First: who sends how much, from which device, under which retention — then the licence.
