A multipart email is an email message that contains multiple content parts within a single send. The most common multipart format includes both an HTML part and a plain text part. Multipart emails improve compatibility because recipients can view the version their email client supports best, and they provide fallbacks when HTML is blocked or fails.
Common Multipart Variants
The classic multipart setup pairs HTML with plain text email. Some modern workflows also include interactive content. For example, AMP for email emails typically require multipart composition so supported clients can render interactive AMP while others fall back to traditional HTML. That makes multipart design a core discipline: you are not building “one email,” you are building multiple experiences that must stay consistent.
Why Fallbacks Are Not Optional
Multipart is only useful when the parts are thoughtfully maintained. If the text version is empty or the fallback is broken, recipients see a degraded experience. That is why fallback content matters. Your fallbacks should contain the critical message and CTA, not just a placeholder. This is especially important for transactional emails where the recipient needs to complete an action immediately.
How Multipart Interacts With Email Clients
A useful QA step is to inspect the raw MIME parts during testing. Confirm that the plain text part is present, readable, and not missing links or critical context. If you use automated tooling, ensure the fallback is regenerated whenever the HTML changes so the two versions do not drift.
Different email client choose which part to display based on capabilities, user settings, and security policies. Some clients prefer text by default. Others show HTML but allow users to switch. Designing multipart emails means keeping meaning consistent across parts, ensuring links work everywhere, and validating that personalization tokens and dynamic fields render correctly in both representations.
Multipart Email and Topol
Topol supports structured email workflows that make it easier to manage multipart templates and consistent fallbacks, helping teams ship emails that work reliably across clients. Learn more at Topol or sign up at Topol signup.