We have been having issues with a customer that sends us emails from bigfish.com. All other emails come through quickly and without a noticable delay. However emails from bigfish take between 2 and 12 hours before they are delivered. It appears from the headers it gets delayed on the bigfish side but that's not 100% confirmed.
We use a Barracuda anti-SPAM and av firewall and I've even adjusted the SMTP timeout settings hoping that would fix the issue but it has not.
We cannot whitelist bigfishes servers because there are so many and we get many domain spoofed emails that can't be allowed through.
Does anyone have any ideas on this? It's very frustrating and is causing some employees to lose business.
Thanks in advance for your help.