Exchange 2013 unable to send email.

After we changed ISP our exchange server was unable to sent emails to some recipients. The error message it get from other servers was "421 Refused. Your reverse DNS entry does not resolve.". The problem was that ISP does not wrote PTR records in their DNS servers. When DNS records was ok. Problem was still there.
Short investigation show that we had 2 IP adresses on routers WAN interface, and default IP was not the same as dns record points to. The solution is to add NAT rule on the router so that source IP of the exchage server was changed to correct IP.

Import Export menu is grayed out in Outlook

This is usually happens with localized version of Outlook. Greyed menu preventing from making backups, import/export email and adress book. Solution is easy:

• Go to Control panel 
• Clock, Language and region
• Region and language
• Administrative tab 
• On Lnguage for non-Unicode programs press "Change system locale.."
• Select the same locale as selected in outlook.

After OS restart import/export meniu should be functional

Exchange 2013 increasing rules quota

To set the rules quota to 256kb for the user dummy run
[PS] C:\>get-mailbox dummy|set-mailbox -rulesquota 256kb
To make sure that the user has got the new rules size run
[PS] C:\>get-mailbox dummy|fl rulesquota
It should return
RulesQuota : 256KB
To set the quota for all users run
[PS] C:\>get-mailbox|set-mailbox -rulesquota 256kb
To get the quota of all users run
[PS] C:\>get-mailbox|fl rulesquota, alias