Hi, I have set the:
\define( 'NOTIFICATION_BACKGROUND_THRESHOLD', 0 );
...and I whitelisted my forum server subnet on the mailserver on the postscreen and whitelisted it for spam checking. Stil having issues that on some threads posting a reply, or sending a Private message to specific members takes ~5 seconds.
Further investigation turned out that this ONLY happens when the member subscribed to the specific thread, or the member receiving this Personal Message, has a non existing/working email address in their profile. I found out as I was getting "Undelivered Mail Returned to Sender" messages right after sending this member a PM.
I then send a email message from my webmaster address (the same address as used on the forums) from my Apple mail client to this member and I almost instantly received the "Undelivered Mail Returned to Sender" message via email.
It seems to me that there is not much I can do about a member not having a working email address. Some members joined 20 years ago, but still regularly visit or post on the forums. As we have 36.000+ members there is no way I can personally force every member to have a working email address in their profile.
It also seams to me that this should not effect the time needed to post a message on the forums. I am not putting the blame anywhere here, I am just trying to find a proper solution. π