Newsletter partly sent

Hello,

I have created a campaign for 205 people on a WordPress site. Report tab let me see that status in “sent” for all of them but there are still 000000 in “Viewed date” column (about 40% of them !). I checked with some people and they didn’t receive the newsletter… Any idea ? Maximum email sent in an hour is 70. Host is OVH.

Thank you for your help !
David