Even Notepad can edit said file and exchange one character to another. I offer no direct solution.
I use Outlook 2003 and Windows XP Pro. I've configured Outlook 2003 to "allow comma as address separator" and I use Word 2003 as my email editor.
I often generate mail messages through a site which has a mailto link with multiple email addresses separated by commas (for backward compatibility with Netscape Mail, which doesn't like semicolons). It used to be that when I clicked on that link, a mail message was created with the comma separators, but then almost instantaneously the commas changed to semicolons. Sending the message proceeded without a hitch.
Now, somehow, something has changed. The commas don't change to semicolons, and when I try to send the message, it fails with the error "Microsoft Office Outlook does not recognize [the address with multiple addressees separated by commas]. If you have used a comma to separate addresses, click Cancel, replace the commas with semicolons, and then click Send again."
I've verified that the checkbox "allow comma as address separator" is still checked. I've restarted the computer, I've uninstalled/reinstalled Outlook, I've changed *.pst files. Nothing works.
It's maddening because on my laptop computer, with (as far as I can tell) the same software, the same software updates, the same configuration, and the same *.pst file, it works fine (i.e., the commas automatically change to semicolons and the message gets sent).
Thanks in advance.