We are having an issue with DNS. We moved our MX records about 2 months ago from one spam filter (hosted) to another (hosted). Still after 2 months we are seeing e-mail traffic still going through our old one. (About 1-2% - 10-15 domains). Network Solutions hosts our DNS. I have called them twice to verify they aren't caching any old MX records and they insist that they are NOT.
Luckily our old spam filter host still accepts and delivers mail. However I'm now stuck as to why mail is still going to an 2 month old MX record that doesn't exist anywhere anymore.
I highly doubt these e-mail servers from the senders are caching old DNS records. Considering after we made the MX change mail almost immediately started going through the new host.
I'm lost, much help would be appreciated.