During installation of Exchange 2010, it asks for the Microsoft Filter Pack 2 to be installed. However, you still cannot search the attachment in Outlook Web App. You must configure it first. Refer Register Microsoft Filter Pack

Or download the zip file and extract it.

Run RegisterMicrosoftFilterPack.ps1 in Microsoft Management Shell.

Stop-Service msftesql-Exchange -Force; Start-Service MSExchangeSearch

From Outlook Web App, e.g. https://ex1/owa and login as administrator, you could search for words included in attachments (MS word, excel, ppt, txt, etc) but not pdf format.

Configuring the PDF filter for Exchange 2010

download PDF iFilter 9 for 64bit platform

extract and install it.

• Add C:\Program Files\Adobe\Adobe PDF iFilter 9 64-bit\bin to the System Environment variable PATH and restart the Exchange 2010 server.
• regedit

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\ExchangeServer\V14\MSSearch\CLSID\

Create a Key:{E8978DA6-047F-4E3D-9C78-CDBE46041603} and set its Default to PDFFilter.dll

Create a string type: ThreadingModel and set it to Both

Create a DWORD type: Flags and set it to 00000001

As shown below:

• HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\ExchangeServer\v14\MSSearch\Filters

Create a string type: .pdf and set it to {E8978DA6-047F-4E3D-9C78-CDBE46041603}

as shown below:

Start Microsoft Exchange Management Shell

net stop msftesql-exchange;net start msexchangesearch

Restart-service MSExchangeIS

cd $Exscripts

./resetSearchIndex.ps1 -force -all

Wait for the indexing to finish before initiating search.

From https://ex1/owa, you could search the content included in the pdf attachments.

A PDF file created by a PDF Printer cannot be indexed by the adobe iFilter. A PDF file created by Adobe Acrobat professional can be indexed by Adobe iFilter.

However, you still cannot search the content included in the pdf attachments from Outlook, even though you enable the instant search and you can search the content included in the word attachments. Outlook instant search uses the client side Windows Search service.

Windows Search support PDF indexing when a PDF IFilter, such as the Adobe Acrobat Reader or Foxit PDF IFilter, is installed.

To configure Outlook client to search for PDF attachment, go to control panel and find Indexing Option

Click "Advanced" button and click "Rebuild"