>>Any ideas?
>
>A guess, but might it be limitations set by the SMTP server or ISP? Some have limitations such as:
>
>- Total # of messages per hour and per day
>- Total # of recipients per hour and per day
>- Total size of messages per hour and per day
>
>If you hit such a limitation you typically don't get any sort of error message or warning. I don't know how an SMTP server or ISP might respond to a perceived violation, but it's not impossible whatever they do could hang a SEND().
>
>If you have a good relationship with the server owner or ISP you could ask them if they've logged any unusual events around the times you're seeing these intermittent errors.


Thanks Al. We're actually sending to smtp.gmail.com as we use Google Apps for Business.

There should never be a circumstance that .send() completely hangs. What's the point of a timeout if there are scenarios that never time out?

If I can't resolve this issue I'll be forced to dump CDO and use a commercial alternative.

When the black box behaves, it's awesome. When the blackbox misbehaves, you're screwed.