Your software
My Mautic version is: 4.1.1
My PHP version is: 8.0
My Database type and version is: MySQL
Your problem
My problem is:
Hello,
I use Mautic to send my newsletter. It was working fine, and I only had 150 subscribers.
However, for my last newsletter, quite strangely, not everyone received it (including myself, since I’m also subscribed).
I checked the stats for my segment, and it showed 215 subscribers (after removing 5 unsubscribed ones). I gained 50 new subscribers in a week. But when I look at the email in the channel, it shows: 2 pending, 118 sent, 18 opened.
This means it was only sent to 140 subscribers, whereas it should have gone to at least 210. So, I understand that about 40% of my subscribers did not receive my email. (It’s worth noting that all emails are valid, and I regularly clean the list in case of bounce-backs.) However, I don’t understand what happened at all. Also, I don’t know how to investigate or check the logs, and I don’t see any apparent errors.
Could you help me figure out what might be causing this issue? My newsletter is very important, and I’m really worried if not everyone receives it.
I’m even hesitating to send my newsletter next week 
Thank you in advance.