Campaign sending less e-mails than the ones in a .csv list

Using phplist version 3.3.2 in Google Chrome, I am trying to send a campaign to different lists including 17544 e-mails each list. Every campaign I’ve sent for each list is sending between 1.200 and 2.100 less mails than the ones included in the list. Here is an example with a list of 8717 e-mails where only have been sent 6282:

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I want to know why this is happening, If I have any way to see which emails are the ones which are not being sent, and If there is any way to solve this problem.

Many thanks,

Luciano

@LucianoCABJ If you have any subscribers who belong to more than one list then phplist will send the campaign only once. That might explain your question.

Otherwise check for any errors being reported on the event log page.