We currently are planning a migration from Netmail to Zimbra and came across a small issue: lots of users read their emails with Thunderbird through an IMAP connection to Netmail, and we plan to activate the IMAP feature on Zimbra so these users can keep their mail environment.

However, some accented characters often used in French show up as question marks in both the Subject and From fields, and less often, in the body of the message itself, when read from Thunderbird.

When using Thunderbird to access the messages on Netmail, the messages are not affected.

Everything looks fine on Zimbra WebUI.

If we move a message from Netmail (that is correctly displayed) to Zimbra, accents become ?. If we move these messages back to Netmail, they show up normally. We merely drag and drop the messages from an account to another in Thunderbird. So messages are unaffected.

Also, accented characters show as question marks in the message listing view in Thunderbird, but are correctly shown in Thunderbird preview pane.

We found out that messages that have been sent with encoding data in the Subject and From fields don't have this problem. Encoding information is shown this way (quoted from memory): ?=ISO-8859-1?Here's the subject.

I could reproduce this behavior with Opera and Pegasus mail clients, so I confirm this is not client related.

Examples of question marked characters:

As we just convinced a major customer of ours to switch to Zimbra, we don't want them to change their mind because of this.

I can provide screenshots and examples if required.

Moderators: I wasn't sure if I should post this in Migration, Administration of Translation. Feel free to move it as you see fit.