Messages hang

[bobcat]

For the last week or so 1/100 messages going outside our network hang when they're sending. If I do a sendmail -q -v I see this:

354 Enter message, end with "." on a line by itself
>>> .

and it hangs there for about 5 minutes and finally times out.

I'm not sure if this is a sendmail issue or a network issue. Any ideas?