Get a faster connection? ;-)
Additional mailboxes cannot be cached so it requires a roundtrip to the
server to obtain the data each time you access it.
So the bottleneck is likely to be in the connection or in the server
resources.

As an alternative you could try accessing the mailbox via OWA instead.

--
Robert Sparnaaij [MVP-Outlook]
Coauthor, Configuring Microsoft Outlook 2003
http://www.howto-outlook.com/
Outlook FAQ, HowTo, Downloads, Add-Ins and more

http://www.msoutlook.info/
Real World Questions, Real World Answers

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"Yaha" wrote in message
news
I am experience a very slow additional mailbox in outlook 2007 rpc over
https. It is hardly possible to work since there are everything from 5-20
seconds delays when you are trying to work in this mailbox. Does anyone
knows if there are any solutions to this issue? I would be extremely
grateful for any help or solutions.