Thank you very much!
I will continue to pursue the issue with the hosting provider.
They simply push the issue back to me, stating that i have a self managed VPS, the issue is on my side.
Thank you very much for your response. I have opened a ticket with my hosting provider. I still have a few questions besides the potential network issue.
1. The main thing i want to confirm is whether there is any indication in the headers show a problem between my VPS host "sendmail" and the...
I use phpmail on Linux VPS with sendmail. I hear from recipients who get duplicates from time to time. It also happened to me in the past. I finally captured the headers from a recipient today.
It appears that my ISP's MTA was sending the duplicates (i hope i read the headers correctly)...