My ISP provides Junk Email protection and it actually does a good job at this and marks all junk messages with ***SPAM***.
Is there any way I can tell Outlook not to download these mails?
Not really, since this is not something that you have to do in Outlook but which you can do in the web based mailbox of your ISP.
If your ISP doesn’t offer any options to control your Junk E-mail, you can still configure in a way Outlook that will minimize the download overhead caused by Junk E-mail
ISP Junk E-mail options
As your ISP already filters out spam for you, you most likely will also have an option in your web based mailbox to tell it what to do with junk emails. Common options are;
- mark them (like ***SPAM***)
- move them to a folder
- move them to the Deleted Items folder
- delete them permanently
Usually you can combine the “mark them” option with the “move” or “delete” option. Sometimes the “move” and “delete” option are only available in the message rules. In that case you can create a rule to move/delete the messages when it has ***SPAM*** in the subject.
Since a POP3 account can only download from the Inbox folder, moving your junk email messages to a different folder on the server will prevent Outlook from being able to download already identified junk email.
However, if you choose to keep the ***SPAM*** messages, you'll need to login to your web based mailbox every now and then to review and empty the folder to prevent your mailbox from becoming full. Some web based mailboxes provide the option to automatically empty some folders after x number of days to prevent this too.
Consult the documentation of your ISP or contact them to find out which options are available to you.
If you are using an IMAP account, then you can simply unsubscribe from this Junk E-mail folder on your server to prevent the messages from being downloaded.
Another approach would be to set the Junk E-mail folder to only download the message headers for that folder. This way you can still empty the folder from within Outlook but also minimize the bandwidth and (local) mailbox space taken up by the Junk E-mail messages.
To change the synchronization settings for an IMAP folder press CTRL+ALT+S to open your Send/Receive Settings dialog. In this dialog press the Edit… button and select your IMAP account.
Exchange and Outlook.com (Hotmail)
Exchange and Outlook.com accounts do not have a user-configurable option to directly delete Junk E-mail at server level.
Outlook.com should already delete all obvious Junk E-mail message automatically and puts the rest in the Junk E-mail folder.
Exchange behaves much the same way but then the level of “obviousness” is controlled by your Exchange admin.
If you are really short on bandwidth or on an expensive connection, and don’t want to waste any on downloading Junk E-mail messages, you can set Outlook to let your Exchange account work in “Download Headers” mode via the Send/Receive tab (Outlook 2010 and Outlook 2013) or the File menu (Outlook 2003 and Outlook 2007).
Your Outlook.com account can be configured like this in Outlook 2010 and previous by pressing CTRL+ALT+S which opens the Send/Receive Settings dialog. Here, press the Edit… button, select your Outlook.com account and set it to download headers only. Outlook 2013 no longer provides this option as it uses a different method (EAS) to sync your emails.