[plug] lost emails

[David Dartnall]

Perhaps someone can point me in the right direction:
Emails I've been sending over the last few years to
a particular recipient are not now being received by
him. Started about three months ago. And they're not
being bounced - I have had no idea that they weren't
getting there.

I'm using Gutsy Gibbon with Thunderbird and have installed
all updates as they come. I know this is vague but I
don't know what information is needed to troubleshoot.

Where could they have gone? I've always assumed emails
to have been received by the recipient if not bounced.

Regards
Dave Dartnall