That error message is quite clear. Failed to connect to the SMTP server.

Because it started and then stopped after X amount, and has been working fine earlier. It really does suggest that the SMTP server being used is only accepting a certain number of messages before refusing connection. i.e. some limit.

The easy way to test, so to use another SMTP server.

the slightly harder way to test is to use the same SMTP authentication details and attempt a manual connection to the SMTP server to send a test. Bet that it will drop the connection when the module is in the error state.

Looks to be clearly that.

That error above is from dynamic registration, and not the bulk emailer. I've talked w/ the host and they had a queue send interval of 60 minutes that they've changed to 15 minutes. This hasn't changed performance, however. They said it only gets into the queue if they don't get a timely response from the remote host. I've asked them to reduce this even more.

However, the problem clearly seems to be the scheduler and why it isn't actually doing the 50 batch every 2 minutes, or 4 minutes, etc. It is successfully sending the batch of 50, which takes around 140 sec on average, but it is only running every 30 minutes or so. It will show the next start time accurately in an entry, or a running entry, but then it doesn't log the next batch until that 30 minutes or so. 50 emails every 30 minutes. 7200 / 100/hr is going take around 3 days.

So any idea how to get the scheduler to actually do the batches when it's supposed to? Or what exactly the mail server could be doing to make this happen? There are zero smtp errors for the bulk mailer, only one from dynamic forms when someone registers on the site. Thank you!