The preview in the Outlook reading pane ....

Copper Contributor



Some emails I receive load slowly in the reading pane, about 30+ seconds when I click on them in my inbox. This usually happens with mails, with lots of links and graphics, with large newsletters. When I click "Forward" or "Reply", I can read such an email immediately in the draft that opens, without delay.


I use Windows 10 pro (19045.3271) and Microsoft Outlook for Office 365 (16626.20132). All Up to date....


Different accounts, Exchange, POP3 & IMAP, occurs with all of them. I already tried around with moving/ forwarding the mails. No difference. Sluggish loading of original mail, no problem forwarding or replying.


1GBit fiber, 100MBit VDSL & 30MBit wireless network, happens regardless of connection/router. MSI, I5, 32GB, NVIDIA Quadro 1200K, SSD, everything fine, everything up to date. Autostart is maintained and the usual suspects are checked.


Without addins same game, with clean restart too. ESET NOD32 is excluded, mails are loaded completely, nothing with headers or so. No extra firewall.


The problem exists since some time. Original mail sticks, no matter what folder or account it is opened from. Reply & Forward works as expected and the content is there immediately. No matter if the mail has been loaded before or not. In the meantime I open the affected mails (you learn with time where it's stuck) directly via right mouse button and Forward.....


Viewing in the browser works, changing the default browser does not change anything. The phenomenon does not occur in OWA. No abnormalities in browsing, no other graphics problems. Disabling graphics acceleration also brings no change. The security settings in Outlook have not been tampered with. Network settings are reset. While loading the problematic mails, Outlook makes a CPU load between 25% and 35% and shows sometimes "not responding"!

A comparable problem is described here:


Is anyone struggling with similar issues? Is there a known cause?


New profile, deletion of the *.ost file, change of cache settings, change from 32bit to 64bit version, has all already taken place. No difference. Lastly, the firmware of the installed Quadro K1200 was updated, also no change.


Are mails rendered differently when opening and previewing than when forwarding or replying? Fonts or network restrictions can certainly be ruled out, since download and rendering are free of delays when replying/forwarding.....

2 Replies
I have already linked to this post in my post.