We would need something to work with to try to figure it out, like a CNM file and a screen dump how the date displays in the email client. If you prefer not to post it here I can give you an email address to send it to.

Since a few weeks I experience a very odd problem, which I find difficult to diagnose.
Every day I send an email to one of Mercury's mailinglists. But suddenly I didn't see them in my Inbox anymore; several others complained too. After some wild goose chases, I did find them in my inbox, but with a wildly wrong 'date received', e.g. jan. 12 instead of may 12.
Here are some more details which may or may not be relevant:
- The problem only occurs for <local> adresses, and only with an IMAP account. Outside adresses on the mailinglist have no such trouble and neither have <local> addresses using POP.
- I don't think the email-client is at fault: it's the same for several different IMAP-clients, on desktop or smartphone. Smartphone apps tend to 'keep' emails only for a month or so, which means these emails are not downloaded at all.  
- The 'wrong dates' seem to be not totally random but always 4 months back, e.g. Jan 10th instead of May 10th, Jan 11th instead of May 11th, etc. In fact, it may be the trouble started May 1st.
- Checking the CNM-files in Mercury's MAIL directoiries shows the files are present and, opening them with Notepad, I can't see anything out of the ordinary.

It's a big nuisance for my <local> users and I am at a complete loss as to how this can be explained let alone remedied. Thanks for any help!

Mabel