After upgrading OTA the iOS 6 beta 4 everything seemed fine on my 4s, that is until yesterday when I decided to change the number of days email synced for one of my Exchange accounts from 30 days to unlimited. Now I get a lot of email and have over 10,000 emails in my inbox, so it can take awhile to sync OTA, but I've done this before without issue. Yesterday after I made the change the phone started syncing email and during this I sent several emails, which it turns out, were never received and in fact didn't show up in my 'sent items' in Outlook on my Mac. I eventually wound up deleting the Exchange account on my 4s with hopes that recreating it would resolve the problem, it did not. No matter how I tried, I am unable to add the Exchange account back onto my 4s. I had a second Exchange account that was working, but I had not changed the mail sync retention on this account. I have since deleted this account and cannot add it back either. I have done a reset of the phone, wiping it, and still cannot add either exchange accounts. I get past the first stage where it asks for my email address and password, at the second stage where it wants the server name etc, it fails every time. I am also the admin for the exchange server and have verified and even rebooted the exchange server, its working fine and Outlook accounts and OWA work fine. I think its a bug in iOS6 and have posted the bug as I am registered dev. The problem for me is that without the exchange account I have no contacts, schedule or email on my phone and its hard to run a business without this. I can't go back to a previous beta build because they are pulled when a new one is released. I could try I suppose, downloading the beta 4 file and loading that on manually, but I don't have any hope that it will fix the problem. Not sure what to do. I realize the risks inherent in using your primary device with beta releases, just never expected email would get broken like this.
After upgrading OTA the iOS 6 beta 4 everything seemed fine on my 4s, that is until yesterday when I decided to change the number of days email synced for one of my Exchange accounts from 30 days to unlimited. Now I get a lot of email and have over 10,000 emails in my inbox, so it can take awhile to sync OTA, but I've done this before without issue. Yesterday after I made the change the phone started syncing email and during this I sent several emails, which it turns out, were never received and in fact didn't show up in my 'sent items' in Outlook on my Mac. I eventually wound up deleting the Exchange account on my 4s with hopes that recreating it would resolve the problem, it did not. No matter how I tried, I am unable to add the Exchange account back onto my 4s. I had a second Exchange account that was working, but I had not changed the mail sync retention on this account. I have since deleted this account and cannot add it back either. I have done a reset of the phone, wiping it, and still cannot add either exchange accounts. I get past the first stage where it asks for my email address and password, at the second stage where it wants the server name etc, it fails every time. I am also the admin for the exchange server and have verified and even rebooted the exchange server, its working fine and Outlook accounts and OWA work fine. I think its a bug in iOS6 and have posted the bug as I am registered dev. The problem for me is that without the exchange account I have no contacts, schedule or email on my phone and its hard to run a business without this. I can't go back to a previous beta build because they are pulled when a new one is released. I could try I suppose, downloading the beta 4 file and loading that on manually, but I don't have any hope that it will fix the problem. Not sure what to do. I realize the risks inherent in using your primary device with beta releases, just never expected email would get broken like this.
You can downgrade, by manually downloading the iOS 5.1 IPSW file, and option-clicking the restore button in iTunes and selecting the file.
I currently have two Exchange + iCloud syncing calendars, contacts & mail back to unlimited on both Exchange accounts and am able to use everything fine? what version of Exchange are you on? 2007 + 2010 here.
It seems like an issue with the beta, yes. Glad you submitted a bug report. Speaking as someone who is also running the beta on my primary phone (however as a student I am not nearly as reliant upon it as you are), now you know better. It's just not worth the risk using untested software on a work device, even a primary device as important as a cellular phone.
I'm sure you've learnt your lesson though. On a hopefully more helpful note, you do have the option of reverting to iOS 5.1.1. I believe you should be able to accomplish this by either finding the firmware online somewhere (not sure you can download it from the dev center) and restoring. You may also be able to simply restore via iTunes, but you may be required to enter DFU mode beforehand for this to work. One problem, is backing up your data. If I were you I'd try backing up to both iCloud and iTunes before attempting any restore, and I wouldn't count on being able to restore from your backup upon reverting firmware.
Another option is to simply keep using beta 3. Yes, it will expire in about 2 weeks, but this should give you time to prepare for either running beta 4 or reverting back to 5.1.1. Good luck.
You can't downgrade a device to a previous iOS version once you have loaded an iOS beta on it, so I can't even do that.