Sending emails from Dolibarr but are considered SPAM FROM_EXCESS_BASE_64

Hello,

I am submitting to you here a problem that I have had for a very long time with sending emails directly from Dolibarr
60% of my emails are considered spam and do not reach the recipient at all (not even in their spam folder…)

I did some research with my host (o2switch) to see if this was not due to a problem on their side and we have comparisons between an email sent via SMTP from a traditional email systeme and the same email sent via Dolibarr ( with the same SMTP settings)
We noticed that Dolibarr transformed the header of the email and triggered the following security rule: FROM_EXCESS_BASE64

FROM_EXCESS_BASE64 indicates unnecessary base64 encoding, generating a high SPAM score.

I’ve searched and I don’t think we have the possibility to modify this method of creating or encoding headers in the settings.
So I’m calling on you to find out if anyone can have an idea of ​​the solution to find to prevent emails sent from Dolibarr from being unnecessarily encoded in this way…

thanks in advance