Forum Discussion
The default mailbox size for Exchange Online E3 and E5 users is increasing from 50GB to 100GB
Anyone know if Outlook OST can handle that much or if you need to be in Online mode?
I knew 2016 could do 50GB... but i still tried to get my users to stay under 20GB like th older cleints required.
I doubt Outlook's OST can handle a fully-synchronized 100 GB mailbox. You will have to reduce the amount of data you synchronize or connect online. Even the fastest SSD will have trouble with an OST larger than 20 GB...
I have seen Outlook sometimes freezes due to load of emails and it also depends on emails sensitivity and complexity in handling large email files.
I still have Outlook 2013 on my lattitude dell and it is working nicely with 4GB of emails these emails are backed up for 4 years.
i have seen the issue with a person who had 7GB OST file, most of his emails has attached items, i then suggested him to split ost file move to Office 365.
Colwill I've been using Outlook since Outlook 97 (yes, I am that old). And in that time I've seen the client improve enormously in terms of its ability to handle large quantities of email. Even so, I keep my OST to under 5 GB because I know that even with a fast SSD (I use a Microsoft Surface Book II), it's the only way to ensure reasonable performance. Outlook has its moments and a freeze is still certainly possible (and given the way the Gods of IT work, it will happen soon), but generally speaking, the "keep your OST under 5 GB" formula has worked for me.
Supposedly the OST and PST files can grow to be very large. By default, Outlook will only support 20 GB PST and OST files. However, if you modify the registry (we use Group Policy to do this, but you can manually do it as well), then you can increase the supported size. We have supported over 100GB PST files (OST files are the same file type).
Here are the registry keys to add (based on Office version), now have fun with that :)
HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\16.0\Outlook\PST
MaxLargeFileSize REG_DWORD Decimal Value: 102400 (100 GB)
WarnLargeFileSize REG_DWORD Decimal Value: 102400 (100 GB)
