We’re experiencing an issue where some subscribers receive duplicate emails for the same campaign, even though they’re only listed in one mailing list. For example, if we send out a campaign at 1 PM, the same subscribers may receive an identical campaign a few hours later. This issue has led to confusion and frustration among our subscribers, increasing our unsubscribe rate due to what they perceive as spamming.
I am currently investigating possible causes and attempting to recreate the issue to better understand the conditions that might trigger these duplicate sends. Any insight into phpList configuration or known issues that might lead to this behavior would be very helpful.