Error 101 (net::ERR_CONNECTION_RESET): The connection was reset.

I have a form that sends an email and attachment to residents of an HOA. It used to work but now when I try it gives me an error "Error 101 (net::ERR_CONNECTION_RESET): The connection was reset." in Chrome and "The connection to the server was reset while the page was loading." in FF. I have also had someone else try this from another location on their computer and they get the same problem, so I know it's not a local issue.

I called the hosting company and am honestly not sure they guy was wanting to help. He said right away that they change things on mail servers "all the time because of hackers" and I have to have the form send to localhost not to mail.domain.com. I'm not sure how this is set up. I just used the wizard. It's hard for me to believe they made a change that would affect all of WA forms and I wouldn't see a lot of posts here, but I just mention it because he did.

Yesterday someone used the form without sending an attachment and it worked fine then. I also have a similar form that is supposed to upload a file to a database as well as send it to all residents, and I get the same error with that one - so it seems to be something with adding an attachment.

Any help would be appreciated as I'm totally stuck. also, the file is only 46kb - so not large.