MailSpring on Linux ErrorNamespace (IMAP)

The Director of Cybersecurity where I work told me about MailSpring, an email client for Linux (Mac, and Windows) that works with Office 365 without using IMAP or POP. I discovered there is a .SlackBuild for MailSpring.

Being the nerd I am, I check the MailSpring site and found a newer version (1.9.1) than the one listed on Again, being ultra-nerdy, I grabbed the latest .deb of MailSpring and built it using: VERSION=1.9.1 ./mailspring.SlackBuild.

When I ran the newly installed software, I encountered an interesting issue:

When I tried to connect to my (work) Office 365 account, I received the error: ErrorNamespace (IMAP).

After trying–and failing–to find a solution on line, I built and installed the version listed on .SlackBuilds (version 1.7.8). Much to my surprise, I was able to log in (using 2-factor) and read my Office 365 email with no issues.

As an experiment, I upgraded (using upgradepkg mailspring-1.9.1-x86_64-1_SBo.tgz) back the the current release of Mailspring and Yay! It worked fine!

Now it’s time to learn Mailspring and add a few more email accounts.

Happy Slacking!

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