IONOS Email vs Microsoft 365: Which Is Right for Your Business?

IONOS sells its own mailboxes (Mail Basic and Mail Business) and also resells Microsoft 365, so customers see both side by side in the control panel. One is a straightforward IMAP mailbox with webmail; the other is Exchange, Teams and Office. This comparison explains what you actually get on each and when a free provider makes more sense than either.

Quick answer

IONOS Mail is the cheaper, simpler choice for a business that wants email on its domain and uses whatever client it likes. Microsoft 365 is for teams that need Outlook with Exchange features, Teams and the Office apps. Both are paid per mailbox or per user per month. If email is the only requirement and budget is zero, OquMail offers 15 mailboxes free with IMAP and an API.

Feature comparison

• Mailboxes: IONOS sells mailboxes individually or in packs; Microsoft 365 is per user with shared mailboxes free up to a size cap
• Free plan: IONOS sometimes bundles a mailbox with hosting or a domain; Microsoft has no free business tier
• API: IONOS has no sending API; Microsoft offers Graph for mailbox automation, not high-volume sending
• DNS guidance: IONOS configures MX and SPF automatically for domains it manages; Microsoft 365 needs MX, SPF, autodiscover CNAME and DKIM CNAMEs, which IONOS can add for its own customers
• IMAP/SMTP: IONOS supports both with standard settings; Microsoft supports IMAP but has restricted basic auth and SMTP AUTH
• Storage: IONOS Mail Basic mailboxes are modest, Mail Business larger; Microsoft Business plans include a 50 GB Exchange mailbox

Where IONOS email wins

• Lower price per mailbox and no suite you are not using
• Automatic DNS when the domain is at IONOS, including SPF
• Plain IMAP and SMTP that work in any client without modern-auth workarounds
• German data centres and EU-focused contracts, which some customers require

Where Microsoft 365 wins

• Exchange features: shared calendars, room booking, rules, retention and litigation hold
• Teams and the Office apps (on Business Standard) in one licence
• Enterprise-grade security: MFA, conditional access, Defender on higher tiers
• Large default mailbox and archive options

Total cost at 5 and 15 users

IONOS Mail at 5 users is a small monthly sum; Microsoft 365 at 5 users is several times that. At 15 users the gap widens, and Microsoft Business Standard for everyone becomes a real budget line. IONOS-resold Microsoft 365 is generally priced close to buying direct, so the decision is about features, not where you buy.

The free third option: OquMail

OquMail is the option when neither bill makes sense. Keep your domain and website at IONOS, change the MX records (the settings that tell the internet where to deliver email for your domain) to OquMail and add SPF, DKIM and DMARC with the dashboard checking each one live. Every mailbox works with Outlook, Apple Mail or Thunderbird over IMAP, and the send API covers app notifications.

• Free plan: up to 15 mailboxes, 3 domains, 5 GB per mailbox, no credit card
• Webmail included; IMAP/SMTP for Outlook, Apple Mail, Thunderbird and phones
• IMAP mail.oqumail.com port 993 (SSL/TLS); SMTP mail.oqumail.com port 587 (STARTTLS)
• Guided SPF, DKIM and DMARC with live DNS verification; MX is mail.oqumail.com priority 10
• Transactional send API at https://api.oqumail.com/api/v1/emails with Bearer API keys (from, to, subject, html)
• Per-message delivery logs so you can see the exact response a receiving server gave

Verdict by scenario

• Trades business, shop or practice that needs reliable inboxes in Outlook: IONOS Mail Business
• Office that runs on Excel, Teams and shared calendars: Microsoft 365 Business Standard
• EU customer with data residency requirements: IONOS, or Microsoft 365 with EU data boundary
• Team of up to 15 with no suite requirement and no budget: OquMail

Common questions

Can I use Outlook with IONOS email?

Yes. IONOS Mail supports IMAP and SMTP, and IONOS publishes the server settings. Outlook works with the standard IMAP setup; calendar sync is separate.

Is Microsoft 365 from IONOS the same as from Microsoft?

The licences are the same product. Billing and first-line support go through IONOS, and admin access is in the Microsoft admin centre.

How do I move from IONOS Mail to another host?

Copy mailboxes with an IMAP migration tool, then change the MX, SPF, DKIM and DMARC records at IONOS to the new provider. Keep the IONOS mailbox for a week to catch late deliveries.