Retrieve E-mail in In-app in iPhone

Currently my project is working perfectly on IOS development target 3.2 But as soon as i will do development target 4.0 or higher. It gives me error. Following is the error:

Ld /Users/taxsmart2/Library/Developer/Xcode/DerivedData/MessageUI-cmsggqfkxarvsnaizxfrkvsmggwj/Build/Products/Debug-iphonesimulator/MessageUI.app/MessageUI normal i386
    cd /Users/taxsmart2/Desktop/ipad
    setenv MACOSX_DEPLOYMENT_TARGET 10.6
    setenv PATH "/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin:/Developer/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin"
    /Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/llvm-gcc-4.2 -arch i386 -isysroot /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator4.3.sdk -L/Users/taxsmart2/Library/Developer/Xcode/DerivedData/MessageUI-cmsggqfkxarvsnaizxfrkvsmggwj/Build/Products/Debug-iphonesimulator -F/Users/taxsmart2/Library/Developer/Xcode/DerivedData/MessageUI-cmsggqfkxarvsnaizxfrkvsmggwj/Build/Products/Debug-iphonesimulator -F/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator3.1.3.sdk/System/Library/Frameworks -F/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator4.3.sdk/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks -F/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator4.3.sdk/System/Library/Frameworks/CoreServices.framework/Versi开发者_StackOverflow社区ons/A/Frameworks -F/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator3.1.3.sdk/System/Library/Frameworks -F/Users/taxsmart2/Desktop/ipad/libxml -F/Users/taxsmart2/Desktop/ipad/ASIHttpRequest/Frameworks -filelist /Users/taxsmart2/Library/Developer/Xcode/DerivedData/MessageUI-cmsggqfkxarvsnaizxfrkvsmggwj/Build/Intermediates/MessageUI.build/Debug-iphonesimulator/MessageUI.build/Objects-normal/i386/MessageUI.LinkFileList -mmacosx-version-min=10.6 -Xlinker -objc_abi_version -Xlinker 2 -lxml2 -D__IPHONE_OS_VERSION_MIN_REQUIRED=40300 -framework UIKit -framework CoreGraphics -framework MessageUI -framework Foundation -framework CoreFoundation -framework MobileCoreServices -framework SystemConfiguration -lz.1.2.3 -framework CFNetwork -o /Users/taxsmart2/Library/Developer/Xcode/DerivedData/MessageUI-cmsggqfkxarvsnaizxfrkvsmggwj/Build/Products/Debug-iphonesimulator/MessageUI.app/MessageUI

ld: warning: directory not found for option '-F/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator3.1.3.sdk/System/Library/Frameworks'
ld: warning: directory not found for option '-F/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator3.1.3.sdk/System/Library/Frameworks'
ld: warning: directory not found for option '-F/Users/taxsmart2/Desktop/ipad/ASIHttpRequest/Frameworks'
Undefined symbols for architecture i386:
  "_OBJC_CLASS_$_MessageWebLayer", referenced from:
      objc-class-ref in MessageUIAppDelegate.o
ld: symbol(s) not found for architecture i386
collect2: ld returned 1 exit status

Also in above error shows in MessageWebLayer which is same as on github. So What changes i need to do in Build Settings or Development target to run on iOS 4.0 or higher. I tried lots of changes in build settings but then Link in github says MessageWebLayer is not supported in 4.0 or higher. Can any one help me in this matter?

If it is not possible for this code then what other classes in iPhone allows me to retrieve email in In-App??

There is no public api's to retrieve Email Id from Mail app in iOS.