Pick Dodosend if…
Your mail is all Gmail
eM Client reaches Gmail over IMAP, where labels become tags. Dodosend works with Gmail itself: labels stay labels, and from: or has:attachment work as they do in Gmail.
You’re on Linux
Dodosend has a Linux desktop build, as an AppImage, a .deb and an .rpm, next to macOS and Windows. eM Client is for Windows and Mac.
You’d use the free plan for work
eM Client’s free version is for home use. Dodosend’s Free plan covers one Gmail or Google Workspace mailbox, with every feature, at home or at work.
You want mail to come back when it matters
H brings a thread back at the time you type, and ⌘⇧H brings it back only if nobody replies. Scheduled send goes out on time even with the app closed.