Cloud Email Services for Business: How to Choose a Secure Provider
Your on-premises Exchange server is out of support, and the board wants a decision by next quarter. Cloud email services host your business mailboxes on a provider’s servers, so you get email on your own domain without running the hardware. The security, though, depends on how you configure it, not only on which provider you pick.
What Are Cloud Email Services?
Cloud email services are hosted platforms that run your company’s mailboxes, calendars and contacts in a provider’s data centers instead of on your own servers. You keep your own domain, such as you@yourcompany.com, while the provider handles storage, uptime, updates and baseline filtering. Microsoft 365 and Google Workspace are the most widely used examples.
How Cloud Email Works (MX, DNS and Hosted Mailboxes)
Your domain’s MX (mail exchanger) record in DNS tells other mail servers where to deliver your email. Point it at the provider, and incoming mail lands in hosted mailboxes. Outgoing mail leaves from the provider’s servers, which is why your DNS also needs SPF, DKIM and DMARC records that name them as authorized senders.
Types of Cloud Email Solutions
- Mailbox suites: full business email with calendars and file storage, such as Microsoft 365 and Google Workspace.
- Hosted mail servers: a provider runs a mail server, such as Exchange, for you.
- Sending platforms: services such as Amazon SES that send app or marketing email but do not host staff mailboxes.
Cloud Email vs On-Premises Email Servers
| Cloud email | On-premises server | |
|---|---|---|
| Hardware and updates | Provider | Your team |
| Uptime commitment | Provider SLA (Microsoft and Google both publish 99.9% for their business suites) | Depends on your setup |
| Security patching | Applied by the provider | Applied by you, on your schedule |
| Control over data location | Chosen region, within provider options | Full |
| Upfront cost | Low, per-user subscription | Hardware, licenses and staff time |
Benefits of Cloud-Based Email for SMBs
The biggest security gain is patching. Microsoft ended support for Exchange Server 2016 and 2019 on October 14, 2025, so those servers no longer get security updates. With cloud email, the provider patches the mail platform for you.
When On-Premises Still Makes Sense
On-premises mail can still fit when a contract or regulator requires data on your own hardware. It then needs supported software and fast patching.
Is Cloud Email Secure? The Shared Responsibility Model
Cloud email is secure at the platform level, but your configuration decides whether your accounts are. Providers work on a shared responsibility model.
What Your Provider Secures
The physical data centers, servers, network, the mail software and its patches, and baseline spam and malware filtering.
What Your Business Must Configure
User accounts and MFA, admin roles, sharing settings, DNS authentication records, retention policies, mail forwarding rules and how staff respond to phishing.
Main Threats to Cloud Email Accounts
Phishing and Business Email Compromise
The FBI’s 2025 Internet Crime Report recorded about $3 billion in reported losses from business email compromise (BEC), where criminals use fake or hijacked email to redirect payments.
Account Takeover and Credential Theft
A stolen password gives an attacker the mailbox from anywhere, because cloud email is built to be reachable from anywhere. Check for unexpected forwarding rules, which let an intruder keep reading mail after a password reset.
Domain Spoofing
Without DMARC enforcement, attackers can send mail that appears to come from your domain to your customers and suppliers.
Security Features to Look for in Cloud Email Services
MFA and Admin Access Controls
Look for app-based or phishing-resistant MFA, conditional access and separate admin accounts. The FTC Safeguards Rule requires MFA for anyone accessing customer information at covered US financial businesses.
SPF, DKIM and DMARC Support
The provider should support DKIM signing with your own domain and make SPF and DMARC simple to publish. Since February 2024, Google and Yahoo require SPF, DKIM and DMARC from senders of more than 5,000 messages a day to their users.
Spam, Malware and Phishing Filtering
Check what is included, such as Exchange Online Protection, and what costs extra, such as Defender for Office 365.
Encryption in Transit and at Rest (TLS, S/MIME)
Look for TLS between servers, encryption at rest and a message-level option, such as S/MIME, for sensitive content.
Audit Logs, Retention and eDiscovery
You need sign-in logs and mailbox audit logs to investigate a compromise. Retention and eDiscovery tools matter for legal holds and regulated records. Check how long logs are kept on your plan.
Backup and Email Continuity
Provider retention is not the same as an independent backup. Decide whether you need third-party backup so deleted or encrypted mail can be restored.
Compliance and Data Residency (UK and US)
UK GDPR, ICO and Cyber Essentials Requirements
Under the UK GDPR, your provider is a processor, so you need a written contract covering data handling (Article 28). If data leaves the UK, transfer rules apply. Microsoft and Google both offer UK or EU data location options on some plans. Cyber Essentials covers cloud services you use, including MFA requirements for cloud accounts.
HIPAA and the FTC Safeguards Rule for US Businesses
US healthcare organizations need a business associate agreement (BAA) with the provider before storing protected health information in email. Microsoft and Google both offer BAAs for eligible plans. The FTC Safeguards Rule requires covered financial businesses to encrypt customer information and use MFA. Confirm specifics with counsel.
Top Cloud Email Providers Compared
Microsoft 365 (Exchange Online)
The most common choice where staff live in Outlook, Teams and Office apps. It includes Exchange Online Protection and offers Defender for Office 365 as an add-on or in higher plans.
Google Workspace (Gmail)
Browser-first email with built-in filtering, DKIM signing and admin controls, suited to teams already in Google Docs and Drive.
Zoho Mail
A lower-cost suite with custom domains, admin controls and business apps.
Privacy-Focused Providers (Proton Mail, Tuta, Fastmail)
Proton Mail and Tuta offer end-to-end encryption between their own users, and Fastmail focuses on privacy. Check their admin and compliance tools before using them for regulated work.
Prices change often and vary by region and plan, so compare current list prices directly with each provider.
Is Built-In Filtering Enough? When to Add ICES or a Secure Email Gateway
Built-in filtering handles bulk spam and known malware. Consider an integrated cloud email security (ICES) tool, which connects by API, or a secure email gateway (SEG), which sits in front of the mailbox, when you handle payments by email or keep seeing phishing reach users. A useful decision rule: if staff report phishing that got through more than once a month, test an add-on during a trial period.
How to Choose Cloud Email Services: A Security Checklist
- MFA enforced for every user, with stronger options for admins
- DKIM signing on your domain, plus easy SPF and DMARC
- Clear statement of included vs paid filtering
- Encryption in transit and at rest, plus a message encryption option
- Audit logs kept long enough to investigate incidents
- Data location options and a processor contract (UK) or BAA (US healthcare)
- Export tools and a documented exit process
Migrating to Cloud Email Securely
Pre-Migration DNS and Authentication Steps
Audit existing DNS records, plan the MX change, prepare SPF to include the new provider and set up DKIM before cutover. Start DMARC at a monitoring policy so you can see every service that sends as your domain.
Cutover, Testing and Exit Planning
Lower DNS time-to-live values, switch MX and test mail flow both ways. Turn on MFA on day one, and confirm before signing how you would export all mail if you leave.
Your Next Step Toward Secure Cloud Email
The provider you pick matters less than the settings you switch on in the first week. List every system that sends mail as your domain, then compare two providers against the checklist above before you sign. If you would like an outside review of your shortlist or setup, Cyber Security Solutions Ltd offers a free cyber security assessment through our contact page.
FAQs
Cloud email is business email hosted on a provider's servers instead of your own. Your mailboxes, calendars and contacts live in the provider's data centers and are reachable from any device. You keep your own domain name, and the provider handles hardware, updates and baseline security, while you manage users and settings.
For most small and midsize businesses, yes, because the provider patches the platform and runs filtering at scale. On-premises servers depend on your own patching, and Exchange Server 2016 and 2019 lost support in October 2025. Cloud email is only secure if you configure MFA, authentication records and admin controls properly.
Yes. Google Workspace lets you use Gmail with your own domain, such as you@yourcompany.com. You verify the domain, point its MX records at Google and add SPF, DKIM and DMARC records. A free personal Gmail account cannot send as your business domain with full authentication, so use Workspace for business.
After cancellation, providers keep data for a limited period and then delete it, and the exact window varies by provider and plan. Export all mailboxes before you cancel, using the provider's export or migration tools, and move your MX records to the new service first so no incoming mail is lost.
Email hosting runs staff mailboxes where people read, send and store mail, such as Microsoft 365 or Google Workspace. An email sending service, such as Amazon SES, delivers mail from apps and websites, like receipts and password resets, but has no inboxes. Many businesses use both, each authenticated with SPF and DKIM.
Not usually in the full sense. Providers keep deleted items and offer retention policies for a set period, which helps with accidental deletion. That is not the same as an independent backup you control. If losing mail would hurt your business, add a third-party backup that stores copies outside the provider.
