error failed: sending email to xxxxxxx

I've checked and double checked all email settings, and see no reason for the following to occur. When sending with Tools > Send Email, I've 233 recipients. Once send has occurred 83 of those email recipients display in pink on a header in the ZenCart Admin with the message Error: failed sending email to: xxxxxxx. This started occurring about 3 weeks ago, and nothing has changed. No sending cap limit exists with my ISP, and I know these to be valid emails, as one is my own.

Is it always the same 83 ? I would check the email addresses around the point it's failing to see if they're all valid.

I know that my email address, which is one of the 83, is valid. Please help

I will test your theory, that there is an error in the first email address where the failure occurs, causing the email addresses that follow to fail. I don't want to send a lot of emails to my customers, so I will wait a couple days.

Tip: Use the Email Address Exporter plugin (see the Plugins area above) to export the list of emails (to screen, to CSV, whatever) and review the addresses for errors.
That plugin uses the same pulldown-menu choices as you have in the other screen, so you should be able to choose the same list that you were sending to, in order to preview the addresses.
Then go fix whichever address is bad.

Issue was that I had exceeded the sending limit with my ISP.

sjdeines:

This started occurring about 3 weeks ago, and nothing has changed. No sending cap limit exists with my ISP, and I know these to be valid emails, as one is my own.Looks like something changed without your knowledge.
sjdeines:

Issue was that I had exceeded the sending limit with my ISP.That seems a very tight limit.
What is their actual limit per hour?
Maybe time to look for a new host!