Incoming e-mail settings missing in document library created with custom document library definiton

I have a custom document library definition which creates library with custom content type. This defintiion works fine except that I don't see "Incoming e-mail settings" under "Communications". This is how my current documentlibrary.xml in the ListTemplates folder looks like: 

<?xml version="1.0" encoding="utf-8"?>

<Elements xmlns="http://schemas.microsoft.com/sharepoint/">

<ListTemplate

Name="DocLib"

Type="10101"

BaseType="1"

OnQuickLaunch="TRUE"

SecurityBits="11"

Sequence="120"

DisplayName="My Document Library"

Description="My Document Library with my Document Content Type"

Image="/_layouts/images/itdl.gif"

DocumentTemplate="101"/>

</Elements>

Interestingly, if I changed the Type attribute to Type=”101” that seems to fix the issue and I could see the Incoming e-mail settings for all the new libraries. But it breaks all the existing libraries that were created using this definition. My two questions for you gurus are:

1.     Is it not the best and the recommended practice to use an integer above 10000 for custom lists? Why don’t I see the link for Incoming e-mail settings when I do so.

2.     Is there a way to fix the existing document libraries if I opted to go forward with Type=”101”?

Thanks in advance for your help.