changed timestamps on my emails

[Ondřej S. <on...@sy...>]

Hello,
hopefully I'm posting this to the right place. I'm trying to figure out
what I did "wrong".
I'm using `aerc` email client which is set to use maildir and mbsync
to synchronize email on Fastmail server to my local machine. It works good
and I've been using it for more than a year in this setup.

Today I decided to create some folders so I used webmail to create
folders and synced them. I then proceeded to use `aerc` email client
and move the emails to my new folders. I then synced my email.

When I was finished I noticed something unpleasant. Other email clients
than `aerc` started displaying wrong timestamps on those moved emails.
The timestamp is now basically today's date / the time when the move
occurred. This happens in web mail client and also in iOS Mail app.

I would like to fix this somehow as I think the temporal information
is quite important. `aerc` still displays the correct timestamp so it
seems like it's not lost but other email clients default to some
different timestamp.

I did write on `aerc` IRC channel to see if the client could have messed
up the timestamp but the answer was that most likely that's not the case
and this is something which is probably caused by IMAP itself - sorry I'm
not an expert on email technology so that's as much as I can interpret
it.

This is what my `~/.mbsyncrc` file looks like:

```
IMAPAccount account.com
AuthMechs Login
Host imap.fastmail.com
User us...@ac...
PassCmd "gpg --decrypt --no-tty ~/mail/account.com.gpg"
SSLType IMAPS
SSLVersions TLSv1.2
Port 993

IMAPStore account.com-remote
Account account.com

MaildirStore account.com-local
SubFolders Verbatim
Path ~/mail/account.com/
Inbox ~/mail/account.com/INBOX

Channel account.com
CopyArrivalDate yes
Far :account.com-remote:
Near :account.com-local:
Patterns "*"
Sync All
Create Both
Expunge Both
SyncState *
```

Would `CopyArrivalDate` cause this? It's long time since I set up mbsync
and I forgot why I adeded it there.

I would be glad for any help that I can get. Thank you very much.

Ondrej