Plain-Text Email vs HTML Email: What's the Difference?

Plain-text email contains only text, formatted exactly like a personal message with no images, colors, or design elements - which also means it can't carry the tracking pixel used to record opens.

HTML email supports images, custom formatting, branding, and buttons, and its underlying code can include an open-tracking pixel and clickable, trackable links - but that same visual richness is also what signals "marketing message" rather than a personal one to both spam filters and the person reading it.

Plain text has historically had a real deliverability edge specifically because it resembles a personal message closely enough to bypass some spam filtering, and plain-text emails have shown meaningfully higher open rates than heavily designed HTML equivalents in head-to-head comparisons. That advantage isn't absolute, though: more recent deliverability data has found plain-text messages to smaller businesses getting blocked more often than lightly-formatted HTML, because some spam filters now read a message with zero formatting at all as a lower-legitimacy signal rather than a safer one. The practical implications follow from what each format can and can't do: plain text suits cold outreach and anything meant to read as one-to-one, at the cost of losing open-rate visibility entirely, while HTML suits campaigns to an existing, opted-in list where branding and design add real value and the tracking data is worth having. A lightly-styled hybrid, sent as multipart MIME so the recipient's client picks the version it prefers, is a common middle ground rather than treating the choice as strictly one or the other.