1. Pricing and Plans: One key difference between Fastmail and Zoho Mail is their pricing and plans. Fastmail offers a few tiers of pricing plans, ranging from basic to business, each with a different set of features and storage limits. On the other hand, Zoho Mail provides a free plan with limited features and storage, as well as paid plans that offer more advanced features and higher storage capacities.

2. User Interface: Fastmail and Zoho Mail also differ in terms of their user interface. Fastmail has a clean and minimalist interface, focusing on simplicity and ease of use. Zoho Mail, on the other hand, offers a more robust and feature-rich interface with a variety of customization options, making it suitable for users who require more advanced functionalities.

3. Integration with Other Apps: Another difference lies in the integration capabilities of Fastmail and Zoho Mail. Fastmail provides limited integration options, primarily focusing on email-related integrations such as email clients and calendar apps. In contrast, Zoho Mail offers a wide range of integrations with other Zoho applications, such as Zoho CRM, Zoho Projects, and Zoho Meeting, providing users with a seamless experience across various business tools.

4. Collaboration Features: Zoho Mail stands out with its collaboration features that are not as extensive in Fastmail. Zoho Mail allows users to create shared folders, share calendars, and collaborate on emails and documents within the platform. This makes it particularly suitable for teams and businesses that require strong collaboration functionalities.

5. Security and Privacy: Both Fastmail and Zoho Mail prioritize security and privacy; however, they differ in certain aspects. Fastmail boasts robust encryption protocols, including two-factor authentication and encrypted email storage. Zoho Mail, on the other hand, offers advanced security features such as anti-spam filters, phishing protection, and email attachment scanning. Furthermore, Zoho Mail complies with various privacy regulations, including GDPR.

6. Customer Support: Lastly, the level of customer support can also vary between Fastmail and Zoho Mail. Fastmail provides support primarily through email and online documentation, while Zoho Mail offers both email support and access to their extensive knowledge base. Additionally, Zoho Mail provides the option for users to receive phone support, which can be beneficial for users who prefer direct assistance.

In summary, the key differences between Fastmail and Zoho Mail lie in their pricing and plans, user interface, integration capabilities, collaboration features, security and privacy measures, and customer support options.