Sending Mails really slow

Hello all,

I’m using the Newsletters Plguin for the first time but sending mails is really slow. It seems, that it always sends out only one mail independent from the values set for “mails per hour”. So I changed NEWSLETTER_CRON_INTERVAL to 2s, so at least every 2s a mail is sent. But it is not. If I update the cron job manualy every 2s, it works and the sent mails displayed for the newsletters is increasing accordingly. If I do nothing, it sends maybe 3 Mails in 2min. What can I do about that?
I already read “Delivery Speed And The Cron Problem” several times but it couldn’t help me.

How can I make it to send more than 1 mail per cron job? I used another plugin to send newsletters before on the same server and it worked. So I don’t think the provider is the problem.

My status:
Sending an email is taking more than 1 second, rather slow. Read more. Average time to send an email: 1.78 seconds
Max speed: 2026.91 emails per hour
Max mean time measured: 3.22 seconds
Min mean time measured: 1.46 seconds
Total email in the sample: 37
Runs in the sample: 37
Runs prematurely interrupted: 0.00%

Newsletter version 7.0.0
NEWSLETTER_MAX_EXECUTION_TIME Not set
NEWSLETTER_CRON_INTERVAL 2 (seconds)

Thanks for your help!
Suse