Mail Preference keeps changing since High Sierra Update

I was also having this issue after upgrading from Mavericks to High Sierra (yeah, big jump!). It was not only happening for Mail but other apps, it was basically forgetting the preferences and some settings from Mavericks were not moved over. I just completed a NVRAM reset and mail seems to be ok and so do my other apps now.

To complete the NVRAM reset do the following...

• Quit all apps
• Shut down the Mac
• Unplug for a minimum of 30 seconds, coffee or bathroom break is best 😉
• Power on the Mac and hold down Command + Option + R + P (YES, all 4 keys at the same time) as soon as you power on. Continue holding the keys through the first beep (if we can even call it that) and DO NOT let go until you hear a second beep. All done!

You will instantly notice your screen brightness reset, proving the NVRAM reset is complete.

Hope this helps, best of luck.

This Apple article might help - How to reset NVRAM on your Mac - Apple Support

P.S. I don't have a 10.13.2 update available yet... Do you?

It happens on a new iMac, MacBook Pro and old iMac. Definitely an iOS bug. It's quite annoying as each time it fails to keep my classic preference, my mail boxes and toolbar are arranged to a default and I need to manually adjust them to what I like. Hopefully it gets fixed.

I prefer the Classic Layout, and the same problem happens to me, too.

In addition to the layout setting, settings in the General and Composing tabs also automatically get back to the default several times a day, which is very irritating.

I have reported it to Apple as a bug, and am waiting for an update to fix it.

I am having this issue with MAIL ever since upgrading to Sierra. happens every 1-3 times I load and use MAIL. I go to trouble of resetting the VIEW as I want it and the thing changes back the next time I load it.

I don't use Classic layout, but I am losing the order of my accounts under Mailboxes/Inbox, and I lose my Preferences->Viewing->Show most recent message at the top preference every few launches. Super annoying..

Agreed. Definitely not fixed in 10.13.1. Maybe no one at Apple actually uses their own Mail app. Or maybe they just want their customers to stop being old-timers and give up using the Classic (and best, to my mind) view.

Not only the classic view, but also other settings such as the frequency to check incoming mails, location to save attached files, using bold font for unread mails and plain text for message format, are all reset and changed back to the default. So this is apparently a bug rather than Apple’s conspiracy (^^

With me it has started after applying High Sierra and still contines even after 10.13.1 update, but I think I have found a workaround to minimize its inconvenience.

Until recently, every time the Mail settings changed back to default, I set it up again as I want, which was very irritating. But once, when I just quit Mail and restarted it rather than resetting it, my original settings came back ! Just restarting the Mail app is much easier and less time consuming than totally resetting it.

Next time you encounter the bug, please try this and check if it also works for you.

Ok, so I'm not alone. Had this happening to me since upgrading to High Sierra, and again this morning it switched from Classic Layout to the modern one. I'm currently running macOS 10.13.1 with all the patches, so I know it's not an issue of needing to update.

Apple, for heavens sake, please fix this. For those of us who use your mail client, it's beyond annoying. What is happening to the QC at Apple??

EXCELLENT point. And thank you for providing the direct link. I have done exactly this now. Others experiencing this issue should do the same. I'd say be as specific as possible, but the box they provide is rather limited in how many characters you can type.

Same here. So I caved and went with the 'modern' instead of the classic design. Only issue now is that the newest responses that I like to have on top keep going to the bottom. I have to open prefs and click the box again and again and again and...........

I will add myself to the list of people that are experiencing the same problem. I have a mid 2011 iMac and had no problems until the upgrade to High Sierra. It is so sad that Apple is now releasing software the same way Microsoft does, full of bugs and things that instead of enhancing the user experience are making it worse. The same thing happened with the latest version of IOS 11 and HomeSharing, it doesn't work properly and there is no fix in sight. At this rate, it will make more sense to buy Microsoft products. They may not be as good and they are more prone to viruses but for the average user like me, it will be cheaper and easier in the longrun