How to remove duplicate sent emails in Fastmail caused by K-9 Mail quirk

I use K-9 Mail on my Android phone as my email client. It’s ugly, inelegant, and quirky, but it works, and has all the functionality I need.

One of its quirks is that if, under Account Settings > Folders > Sent folder, the folder is set to “Sent”, I end up with duplicate copies of every email I send in that folder. I’ve been using K-9 long enough that I’ve ended up with thousands of duplicates like this.

Fortunately Fastmail, my email service provider, has an easy way to address this:

This is a utilitarian feature that allows duplicates in a selected folder to be eliminated. I did this yesterday, and it worked like a charm.


Ton Zijlstra 's picture
Ton Zijlstra on May 4, 2020 - 11:55 Permalink

I have the opposite issue. I can't get K9 to save a sent message to my imap folder

Brandon Blackmoor's picture
Brandon Blackmoor on January 10, 2023 - 13:04 Permalink

In K-9, go to Settings, Sending Mail, and scroll down to the bottom. There is a setting for "Upload sent messages".

If you are using Fastmail's server to send email from K-9, Fastmail will (by default) automatically save a copy in "Sent". You do not need to select "Upload sent messages" in K-9.