one address rejected so group not sent

Hi biswas

I would split the group in half to see which group failed at that point.
Then you are left with only 15 addresses to check out.
Repeat the same procedure from there.

Does a different address get rejected each time this has happened?

Do the e-mail addresses being rejected share the same domain?
Have you tried the list in another e-mail client such as Outlook or Thunderbird?
In Outlook Express,
Tools > Accounts > (Account Name) > Properties > General tab
Do you have an e-mail address in the Reply Address: field?

See this link for additional information:
http://insideoe.tomsterdam.com/problems/errors.htm#errsend

The next time you receive the error, can you post the exact error message, please.

Hopefully the error message will give us a clue.