trouble injecting bounce message

[Joel Gautschi]

hi,
I have a lot of these entries in my /var/log/syslog file. what do these
entries mean? do I have to care about them or are these messages just
'information'?

Aug  3 06:26:22 joshua qmail: 965276782.869518 warning: trouble injecting
bounce message, will try later

thanks for an answer
Joel