I have found a fix for this. It is not very graceful, but it works. Unfortunately, it requires a second mac.
I renamed mail.app to mail 1.app. Then copied the mail.app from another computer to the ailing system. The next time you enter passwords, it will remember it, sometimes it will find the keychains and the passwords do not have to be entered again.
I have mail.app saved on my system for when it happens again. I have not been able to figure out what is making mail break like this. Though it was my .mac account, but now I think the source might be syncing my iPhone email accounts. Time will tell.
I will look at the dvd install disk and see if there is a way to extract the mail.app file from the install disk in case you only have one computer.
I have called apple on this. Do not reinstall your system. It does not help.
If you only have one computer, try this...
Backup your email - this is found in the mail folder in your home folder library just make a copy of it and put it somewhere safe
insert your leopard installation dvd
choose the optional installs folder
now choose the optional installs.mpkg
agree to everything and when you get to the custom installation window that has the application folder, open it and choose mail.
Install it and test it
this should work. If it does, let me know (or I will try it next time my mail program breaks and I will let you know). If it does, duplicate the good mail.app program and put it somewhere else on your drive when the keychain breaks again, and follow the previous post so you do not have to get your installation dvd out every time the program breaks.
Hope this works for you (us).
okay, but does reinstalling mail work? Your expections are one thing, but while they work on a fix (the problem has been sent to their engineers), it is the fix that counts.
My mail has not lost the passwords again, so I can't test it. Anyone try my reinstallation recommendation? I know the first fix works, but it does not help others who do not have a second computer.
Thanks for your suggestions. I'll try them on the weekend when I have more time and report back. Sorry for the delay in replying. Ironically, when I went to retrieve my emails in Mail relating to this posting, I was prompted for my password, so the problem still exists. Hopefully your suggestions will help.
I'm having the same problem as well, I have have been involved too long with software support to go with the 'just reinstall and it should be fine' approach.
Here is some diagnostic info:
I'm running the latest everything (OS X, 10.5.1, Mail Version 3.1 (914/915)). I have four accounts, the first is my .mac (which I don't believe forgets my password, but I don't get much mail to that account). The second is my regular work email which gets a lot of email, and am frequently prompted for my password. The last two are personal accounts and get less email, but I have been prompted for passwords for them. Except for my .mac account, the others are all pop3 servers. I doubt that it matters, but the other three are all yahoo accounts.
My theory is that it happens with the pop server doesn't respond quickly enough so mail thinks that the credentials have been rejected and prompts for a new password. I checked in the mail configuration for accounts and the wait parameter is not settable.
Has Apple logged this as a bug? Seems like we can't be the only people having the problem.
Having the same problem here. Although I can send and receive mail I am getting the 'Enter Password' dialogue box appearing all-too frequently. The password obviously works but the Keychain seems to keep forgetting it - and I've run Keychain First Aid to no avail.
It seems to be a bug in Mail. This is a minor irritation but it just shouldn't be happening in Leopard. Bug fix please Apple.
In the meantime I'm going to try Thunderbird.
After repairing mail with the app program from another machine, the .mac settings I have right now do not cause the problem to recur.
contacts, safari, ical and do NOT merge on a sync. I have not been brave enough to try variations to see what breaks mail passwords. I know this limits some functionality of .mac, but for me at least it is better than entering my passwords over and over.
I was having this same problem. It just started recently, I believe after an update, but didn't pay enough attention to be sure. Anyway, I just tried brothma's solution of reapplying the patch and it did, indeed, fix the problem. I had to enter the passwords again the first time I started Mail, but now I can quit and restart without entering all of my passwords (for 6 servers) every time. Hopefully 10.5.2 fixes this for everyone. Thanks for the tips.
This happens to me frequently (multiple times a day). Running 10.5.1. I've done a complete archive and reinstall, and then an install of the patch (on people's advice based on problems I was having (one of which turns out to be the still-a-bug Lightroom JPEG/Leopard problem). I am just going to live with it until 10.5.2, but I wanted to register another user who is having this problem and can't wait for a fix.
Hopefully, Apple is paying attention. I'm a developer who switched to Mac on hopes of extreme "reliability and stability", that have really not been met under Leopard (a good example besides the mail problem, is how files with "unexpected" metadata crash Finder and apps that use certain Apple subs under Leopard, but not Tiger or Windows).