E-Mail sendt from my ISPConfig are sometimes treated as spam

E-Mail sendt from my ISPConfig are sometimes treated as spam.

i have chekced here and everything is OK.
https://mxtoolbox.com/SuperTool.aspx?action=blacklist:isp1.tten.no&run=toolpage

have listed my mailserver here:
https://www.dnswl.org

i also have reverse dns on servers ip.

is it more i can do?

 

is there a guide on howto do this?

 

main problem is with gmail

 

see this manual but is this necessary in a newer version?
https://blog.schaal-24.de/ispconfig/ispconfig-dkim-patch/?lang=en

cant find anyhing about this in the ispconfig manual also

 

Gmail mail header. can it be because sender is:127.0.0.1 ?

 

i have also added:
TXT/_dmarc.domain/v=DMARC1; p=none
TXT/domain/v=spf1 mx a ~all

now i get perfect score at: https://www.mail-tester.com

I hope this fixes my problems. thanks for all help