Skip to content
This repository

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP

Frequently Asked Questions (FAQ)

Where did the name 'K-9' come from? What's with that icon?

How do I prevent K-9 Mail from reporting unread messages I already read from my desktop? I'm using POP3.

How do I get back to the accounts overview screen?

Why can't I move K-9 Mail to the SD card?

How do I change my Signature?

How can I configure the Archive, Drafts, Sent, Spam and Trash folders?

How can I attach *.xyz files?

Why aren't my settings saved?

Why does "Mark all messages as read" say that there are messages I can't see?

K-9 is taking ages to fetch messages, help!

I'm having some trouble with a lot of concurrent connections to my IMAP server

Why K-9 is using so much bandwidth to sync my POP mail?

K-9 is crashing, please help!

Where is the source code?

Why are there no release notes/list of changes for version X?

What is the difference between version 4.0xx and 4.1xx?

What is the difference between pushing and polling?

Why is K-9 telling me, "Syncing disabled"?

I added a new folder to the account on the server, but I don't see it in K-9

How do I add additional Mail Accounts

How do I add Unified Mail Inbox

Where did the name 'K-9' come from? What's with that icon?

In some incarnations, Doctor Who had a robotic dog named "K-9" The dog was, in effect, an android mutt. When Jesse first created K-9, his goal was to create an Android mail client as good as the UNIX mail client mutt. The name was a natural fit.

K-9's icon is a picture of...well, of K-9.

How do I prevent K-9 Mail from reporting unread messages I already read from my desktop? I'm using POP3.

This is a POP3 limitation: that protocol doesn't report/support READ/UNREAD status. IMAP addresses this limitation.

How do I get back to the accounts overview screen?

If you see a list of mails inside of a folder and you want to get back to the overview screen, you have to

  • Press the menu button
  • Select "More"
  • Select "Accounts"

Why can't I move K-9 Mail to the SD card?

Google doesn't let programs installed on SD run as services, which we need to do in order to be able to fetch your mail.

How do I change my Signature?

Do the following to replace default signature in K-9 with your personal signature for any email account or stop K-9 default signature for that particular account:

Open K-9, select email account in which you wish to create a signature. Key Sequence: Menu/Settings/Account Settings/Sending Mail/Composition Defaults

In this dialog, you can enter Your Name, Your Email Address, Bcc all messages to, CHECK (or uncheck) USE SIGNATURE, enter your signature using correct syntax of top line of signature with -- followed by a line break, and enter your desired signature. Choose radio button to place Signature position before or after quoted text.

How can I configure the Archive, Drafts, Sent, Spam and Trash folders?

"Account settings" (via long click or Menu) > "Folders" ("Incoming server" in pre-3.400 versions)

How can I attach *.xyz files?

K-9 Mail uses the standard Android way to inherit external app features (Intents); you need a file manager application in order to choose any file.

Compatible file managers:

Why aren't my settings saved?

Please use the Back key to leave all settings screens in order to trigger settings save.

Why does "Mark all messages as read" say that there are messages I can't see?

K-9 lets you choose to only sync the most recent messages to your phone. This particuar feature operates on all messages, even if you've chosen to sync only the last 10 messages to your phone.

K-9 is taking ages to fetch messages, help!

Some device have very inefficient storage. Try switching storage (3.400+ only).

I'm having some trouble with a lot of concurrent connections to my IMAP server

You've turned on "push" mail and marked a lot of folders for push. IMAP push requires one connection per folder.

Why K-9 is using so much bandwidth to sync my POP mail?

K-9 normally doesn't take much bandwidth. It is comparable to other Android mail applications such as GMail. However, there may be some situations where K-9 can consume up to 150k of bandwidth everytime an account is refreshed.

This normally happen when you have a POP account that has a huge inbox folder. If you have a inbox of about 2500 messages in it, it would generate data exchange between K-9 and the POP server in the order of 120k per refresh query.

To prevent that to happen, you simply have to move all these messages in another folder in your account. We don't recommand to keep all your incoming messages into the inbox of your POP account.

K-9 is crashing, please help!

If you can't find a similar problem at http://code.google.com/p/k9mail/issues/list, please file a new issue and provide a debug log and detailed steps on how to reproduce the problem if possible.

Where is the source code?

https://github.com/k9mail/k-9

See also: How to build K-9 Mail.

Why are there no release notes/list of changes for version X?

We only publish release notes for stable releases (see next question) that are also pushed to Google Play (formerly Android Market).

What is the difference between version 4.0xx and 4.1xx?

In short:
4.0xx = stable / Google Play (Market)
4.1xx = unstable / development
4.2xx = the next stable
4.3xx = the next development

See the pattern? If the digit after the dot is even, it's a stable release. If it is odd, it's a development release.

Stable releases are changed only minimally when necessary, and should work just as well or better for all users when changed (i.e. going from 4.004 to 4.005). These are released to Google Play (formerly Android Market). It's a good idea to always update these, as they contain serious bug fixes and security updates, but you probably won't see anything different.

Development releases are the latest and (hopefully) greatest, but may introduce new bugs or break things that were working before. You might find that K-9 no longer works on your device with an older version of Android (somewhere in 4.1xx we quit supporting Android older than 2.1, which means that K-9 4.2xx will only support Android 2.1 and newer). This is where new features happen (as well as bug fixes and security updates), and by using development releases you can help us to spot and fix new bugs early.

Every version of K-9 is available to be downloaded here. They are sorted by date, most recent first, and you can see that some 4.0xx releases are listed above some 4.1xx releases. Often a 4.0xx release will happen at the same time as a 4.1xx release.

What is the difference between pushing and polling?

Depending on what type of account you have configured, K-9 may support either push or poll for fetching new mail (see Account settings > Fetching mail). At this time, K-9 only supports push for IMAP accounts. Polling refers to the mail client periodically asking the mail server for new mail, on some configured time increment. Pushing refers to the mail client keeping an open connection to the mail server, so that the server can inform the client of new mail as soon as it is received. Pushing typically uses more battery for a few reasons. First, when you have any account configured to push, this keeps an Android service running at all times. This service keeps 1 open connection to the mail server for each folder configured to push (which also uses battery power). And lastly, pushing will typically lead to more frequent communications between the client and the server.

Why is K-9 telling me, "Syncing disabled"?

It will say this if there is no network, or if there are no folders set up to pull or push (inbox by default will), or if pull and push are both disabled, or if syncing is disabled for all K-9 accounts.

Most of these settings are under Settings > Account settings > Fetching mail. See Folder poll frequency, Poll folders, and Push folders. To change a folder's class, long-press on the folder and select Folder settings.

The global K-9 setting is under Settings > Global settings > Network > Background sync.

I added a new folder to the account on the server, but I don't see it in K-9

K-9 currently does not automatically update the list of folders. To refresh, while viewing the current folders, select Menu > Folders > Refresh Folders. This will also delete folders from K-9 that have been removed from the server.

How do I add additional Mail Accounts

This was tested in Galaxy S3 k9-4.409

When you start K-9 it goes to the inbox (or Unified Inbox if that is setup)

1) At the top to left of the word Inbox there is the Dog Icon and to Left of that is a small < (less than symbol once)

2) Tap once brings you to folders

3) Tap it a second time brings you to Accounts

4) Now from that screen you can tap the menu button (left of home button on G3). That will pop a menu where the first item is "Add Account"

Note: If you are using Unified inbox, you only need to tap the < (less than symbol)

How do I add Unified Mail Inbox

1) Start K-9

2) Tap Menu > Settings > global settings >Interaction

  • check the "start in Unified Inbox option
  • Tap return to set
Something went wrong with that request. Please try again.