Issue with Outlook 2013 and connecting to exchange 2013 server

We have a very strange issue that is happening very randomly with some users.
Their outlook will sometimes sits there and tries to connect to the exchange server and then eventually will connect. sometimes the outlook will have emails sitting waiting to send and then sometimes this go out and other times they have to close outlook and reopen it then all seems to be ok.
This is a very intermitten issue and is only happening with some users. To me it seems like a cimmunication issue possibly with the network.
Had anyone ever seen this and if so what can I look at?
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Zaheer IqbalTechnical Assurance & ImplementationCommented:
Have you to tried re-creating user Outlook profiles to see if it fixes the issues ?
Hypercat (Deb)Commented:
Are you using cached mode?  Just wondering if it might be a problem with the local OSTs getting too large, fragmented, or otherwise having issues updating from the server.  You might want to try changing to online mode to see if that improves the experience, unless there's a reason that online mode won't work in your environment.
vmichAuthor Commented:
Found the issue.. We had a denial attack on one of our other servers that was causing all of the issues. Once this was resolved, the outlook issues all went away

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vmichAuthor Commented:
Denial attack on network server
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