Error in downloading mail on IMAP after ios 18 upgrade

Yes, this has to be an iOS 18 issue. My MacBook Pro and Mac mini can access e-mail without a problem, but my iPhone 12 and partner's iPhone 16 (just purchased last week) aren't showing recent e-mails.

I have the same problem with my email, French internet access supplier, Free. It’s impossible to send email: Network error: (posik 96) It’s only with IPhone on IOS 18, not before, and not with my IPad or Mac. Apple Store wasn’t able to fix the problem. And it’s impossible to change for IOS 17. Then I can’t send email with my iPhone. When Apple will fix this bug??

I have exactly the same problem.

Tried to fix this, not sure but it might have to do with the certificates being self signed with dovecot.

Sending emails is possible in iOS18, only receiving en viewing the imap mail content is not possible in iOS18 in combination with dovecot.

I hope they fix this because this is one of the most essential functions of the device.

I have a dovecot/postfix server as well and am using lets encrypt for ssl, and am experiencing this issue too. I do not think it's an issue with self signed certificates.

No VPN here either.

Curious, has anybody brought this up on any Dovecot mailing lists yet? Or somewhere else? I am looking at their recent archives and see nothing. I do see this mentioned on Mac Rumors forums.

I have dovecot 2.3.19.1 (9b53102964) on a stock Debian 12 system at the moment. Postfix is working fine.

I'm not using any other server or VPN, just the mail app provided by Apple and the standard configuration on the iPhone, upgraded to 18.1.1 and the problem persists. I get mail on my PC through iCloud and that's working fine. Mail will drop on the iPhone ocasionally but does not reflect what is on the iCloud server, i.e. deleted on server shows up as unread on app...

“Those here running their own server, I'd like to hear what your folder separator is set to. If you change it to anything else, I expect your connection problems will go away.”

I am running a dovecot server, and I will have to figure out how to check the configuration for this information. However, I believe the separator is a dot, because I can’t create an imap folder name with a dot in it (I.e. purchases.home becomes purchases with a sub folder named home)

plinss wrote:

https://doc.dovecot.org/2.3/configuration_manual/namespace/

In my case (Debian), it's in /etc/dovecot/conf.d/10-mail.conf, look for 'namespace inbox'

Thanks again. This morning I looked at my server configuration. (I installed Postfix/Dovecot using the Cutedge Systems GUI called MailServe. So Dovecot is installed at /usr/local/cutedge/dovecot.) The only configuration file appears to be . . . dovecot/etc/dovecot.conf. But that file doesn't contain a namespace setting, so I assume that Dovecot is falling back on whatever the default is.

plinss wrote:

…

Those here running their own server, I'd like to hear what your folder separator is set to. If you change it to anything else, I expect your connection problems will go away.

…

# shared namespace configuration
namespace acl-mailboxes {
  type = shared
  separator = .
  prefix = shared.%%u.
  #location = maildir:%%h/Maildir:INDEX=~/Maildir/shared/%%u
  #location = maildir:/Library/Server/Mail/Data/mail/%%u:INDEX=/Library/Server/Mail/Data/mail/%%u/shared
  location = maildir:/Library/Server/Mail/Data/mail/users/%%u:INDEX=/Library/Server/Mail/Data/mail/shared/%%u
  subscriptions = no
  list = children
}

Interesting, thanks for that. It seems the we're either facing different issues, or there are other configuration settings that impact this. Do note that the excerpt you quoted above seems to be for shared mailboxes, you may have a different configuration for your inbox. Look for a namespace that contains "inbox = yes".

I just re-tried the experiment I tried a few weeks back and setup a test Dovecot server (v2.3.19.1 on Debian Bookworm). Setting the separator character to "\" (actually "\\" because it needs to be escaped in the Dovecot configuration file) causes my iOS mail connections to fail every time. Dovecot log shows a Login immediately followed by "Disconnected: Connection closed (LIST finished 0.009 secs ago)".

When I change the separator character to "/", ".", or "|" it connects and functions fine. Other clients (including Mail on MacOS) connect regardless of the separator character setting.

On my test server the only settings defined in the inbox namespace are "separator", and "inbox = yes" , everything else is the default value which should be equivalent to:

namespace inbox {
  type = private
  separator = "\\"
  prefix =
  location =
  inbox = yes
  hidden = no
  list = yes
  subscriptions = yes
}

Alas:

Changing it from commented out to 'separator = "\\"' broke the server:

Nov 23 17:23:04 imap: Fatal: master: service(imap): child 91197 killed with signal 11 (core dumps disabled)

Changing it to 'separator = .' didn't break the server, but caused a new and questionable error message in iOS only:

Server code "CANNOT", server message "Invalid mailbox name: Name must not have '/' characters. 

Finally, Changing it to 'separator = \\' (no quotes) doesn't hurt (other mail clients work), but doesn't help iOS 18.x.

Here is the section from 10-mail.conf. It is commented out on my installation. I do not have a separator defined, and the installation has worked as expected up until 18.x. and continues to work with macOS mail and other MUAs.

mx:~$ sudo dovecot -n |grep separator

mx:~$ sudo dovecot -n |grep namespace

namespace inbox {

mx:~$

#namespace inbox {
  # Namespace type: private, shared or public
  #type = private

  # Hierarchy separator to use. You should use the same separator for all
  # namespaces or some clients get confused. '/' is usually a good one.
  # The default however depends on the underlying mail storage format.
  #separator = 

  # Prefix required to access this namespace. This needs to be different for
  # all namespaces. For example "Public/".
  #prefix =

Please don't change it to "\\", that configuration I posted is an example of what doesn't work (for me at least).

Note that as I posted earlier, changing the separator is dangerous. On one of my servers I tested changing from '\' to '/' and while that makes iOS able to connect, it also broke MacOS Mail when dealing with mail in nested folders (it might have sorted itself out if I reset the mail account, but that's not an option for all the other users on my servers).

Also, using `separator = \\` (without the quotes) is not recognized by Dovecot, it treats that as an empty (default) separator. You can check this by running `doveconf -a` to dump all the config settings.

Another thing I found during my testing is that I can change the separator to something other than "\\", restart Dovecot, connect my iPhone to that account, then change it back to "\\" and restart dovecot again and the iPhone keeps working. It just needed to get past the initial handshake (and likely the LIST command). If I restart Mail, then it once again fails to connect.

plinss wrote:

Please don't change it to "\\", that configuration I posted is an example of what doesn't work (for me at least).

Understood. I thought it might be a good experiment since my configuration currently seems to use a default separator, possibly a dot. Did trying a forward slash irreversibly scramble your folder nesting or the did the hierarchy recover when you reverted to your previous configuration?

I Just downloaded the update - 18.1.1 - and it’s still the same - not fixed! Extremely annoying, since my iPad is my main email etc when I’m not at work. I can at least access them on my android phone but that is not workable long term! I’m on Yahoo mail, which is what a lot of people used on another site chat stream - from September! Ridiculous it’s taking them this long!