fetchmail dies each time I run it with a 'listener' error or a
'synchronization' error. It is timing out on very small mails, like 1200
octets, and if I use a mail client such as Balsa to check my mail it works
without a hitch, so I know it isn't my ISP.
Can't reproduce it here.
The difference between fetchmail and balsa is that fetchmail uses sendmail for
local delivery (basically, it telnets to your port 25 to deliver its mail).
Check your sendmail installation for configuration errors.