Let me know what you find if you use another Imap. This yahoomail thing drove me nuts last week. I downloaded K9 then uninstalled it just bc. I was disappointed. As I became more comfortable with the phone I downloaded K9 again and have been surprisingly pleased with it and more comfortable. I just wish I could get PUSH to work or have someone confirm if PUSH does not work with K9 and Yahoomail. Honestly, if this works on K9 or they gt it working then the app in my book is worth of a fee and not being free. Especially if they use the revenue to improve the app interface.
Does anyone know of a forum specific to K9 or K9 issues that is active and gets views?
Ok, I've done a bunch of tests and have info.
Bottom line, I was able to get it to work with non-Yahoo IMAP accounts, but apparently Yahoo does not support IMAP push email.
I tried with another IMAP account that I have. I am able to get K-9 to work for IMAP push mode with IDLE support. This means that if I send an email to that id, K-9 immediately notifies me and I get mail.
There is a needed configuration change
In the account, go to the folders view (Menu/Folders). Long press the folder, select settings, assign 'Folder display class' to 1st class.
By default, K-9 is configured to only check for push mail for 1st class folders, and by default, nothing is a first class folder.
You can configure K-9 to receive Gmail. Gmail does support push IDLE.
Meanwhile for Yahoo, I configured it. Ran a bunch of tests. Never worked. Then eventually I noticed that if I look at 'Folder list' for the Yahoo account, there's a folder named 'K9mail-errors'. Inside are error messages that state,
'IMAP server is not IDLE capable'. IDLE is needed to get PUSH IMAP to work.
I was then able to google more for this issue. Turns out that Yahoo does NOT support IMAP push mail. They do support IMAP but only on mobile networks. The solution for iPhone appears to be a custom solution. They apparently send a special SMS message to the phone which the mail application then uses to use IMAP to pull the messages back to the phone.
This is described in a Wikipedia article,
Push-IMAP - Wikipedia, the free encyclopedia
Although they are both based on IMAP, the Yahoo Mail and MobileMe push email services for iPhone do not use a standard form of P-IMAP. Yahoo Mail uses a special SMS message to trigger an email synchronization, while Apple Inc.'s MobileMe uses a server within Apple that maintains a persistent IP connection to each iPhone.[1]
So, bottom line, K-9 does PUSH email, but Yahoo doesn't support it.
I haven't decided what to do about it. The options seem to be either poll Yahoo or have Yahoo forwarded to an IMAP Push capable email address such as GMail. Yahoo IMAP doesn't work over WiFi, but POP does. I'm debating if its even worth using Yahoo IMAP if it needs to poll anyway.