Do multiple email accounts or PST archive files slow down Outlook?

[jmt356]

Suppose a user has 5 email address accounts registered in Outlook. I imagine that would cause Outlook to slow down more than if he had just one or two.

What if a user had 2 email address accounts and 5 PST archive files, with each PST being 5 GB. Would that cause Outlook to slow down more than if he had just 2 email addresses and no PST files? Does the existence of PST files slow down Outlook, even if they are sitting on a hard drive in the background and not actively sending or receiving emails?

My PST files are offline, but they show up in my tree view. They are only active if I open them. I believe they are still operating in the background because Outlook searches the PST files whenever I select "All Mailboxes" in "Search In" and I occasionally get results from my PST files.

If having PST archive folders slows down Outlook, what is best practice? Should users delete PST files with emails more than a certain number of years old?

If PSTs slow down Outlook, is one fix to remove them from the tree view but still keep the PST files on my hard drive? That will trick Outlook into believing that the PSTs don't exist, while allowing me to keep important information without deleting the PST files.

[StuartR]

I have an old email archive. I close the PST file and I only open it if I have a specific need to.

[jmt356]

I have an old email archive. I close the PST file and I only open it if I have a specific need to.

What do you mean by "close"? I have multiple old PST files and 4 active email accounts. I have all my active email accounts expanded in the tree view. None of my PSTs are expanded in my tree view and I never access them unless I am looking for something specific. However, results from my archive files do show up from time to time in my search results. Does this mean they are closed? Or do I actually have to right-click on a PST in my tree view and select "Close" for it to truly close?

If a PST file is in my tree view but I am not actively using it, will it still slow down Outlook?

[StuartR]

To Close an outlook data file right click on the entry in the Tree view on the left of Outlook and select 'Close "datafilename"'
To open the data file again go to File > Open & Export

[HansV]

I have 4 .pst files and 3 .ost files in my list of data files, 6 of which are displayed in the treeview on the left. Two of the archive .pst files are over 500 MB in size. In my experience, this does not slow down Outlook.

[StuartR]

I agree with Hans, the reason that I only open my PST files when I need to is that when they have been opened in Outlook my backup software decides they need backing up, and that can be very slow!

[JoeP]

Most likely the perceived impact on Outlook with multiple accounts is due to the responsiveness (or lack thereof) of the email hosts.

[StuartR]

Outlook takes a long time to start for me on a PC that has 10 different POP3 accounts, each of which gets quite a lot of emails. The delay is just how long it takes to download outstanding messages from each of these accounts when Outlook is started.

[JoeP]

@StuartR, I wonder if you'd be better off not having Outlook do a send on startup and setting up send/receive groups with different timing for each.

[StuartR]

Possibly Joe. But this Outlook instance is mainly an emergency backup, so I generally open it once a day and close it again after it has finished downloading

[jmt356]

I am not referring to Outlook's startup speed. Rather, I am referring to Outlook's general slowness / unresponsiveness, for example, when switching to the Calendar, back to Mail, into the Inbox and then to Sent Items, searching for Contacts, etc. I wonder if having many large PST files in the Tree View impacts speed.

[StuartR]

I don't think that speed of those things would be significantly affected