That's the #1 question in this forum.  See this link for full details:

Microsoft Outlook "Object Model Guard" Security Issues for Developers:
http://www.outlookcode.com/d/sec.htm

How to prevent Outlook security warnings from appearing?
Need to remove security alerts? With Outlook Security Manager you can easily
bypass security settings in MS Outlook and turn off an alert, or a pop-up
message with just one line of code! Unlike similar tools, Outlook Security
Manager doesn't transform OOM (Outlook Object Model) and CDO (Collaboration
Data Objects) calls to Extended MAPI calls and doesn't make development more
complicated by its own special objects. It just implements one object with
three properties that enable or disable security settings for Outlook
objects, CDO and Simple MAPI including MailMerge. These properties are
DisableOOMWarnings, DisableCDOWarnings and DisableSMAPIWarnings. Before
calling a protected object you just switch off Outlook security via the
corresponding property, and then you turn it on again. For example:

Visual Basic .NET

Dim SecurityManager As New AddinExpress.Outlook.SecurityManager  
SecurityManager.DisableOOMWarnings = True  
Try  
   ' ... any action with protected objects ...  
Finally  
   ' In any case please remember to turn on  
   ' Outlook Security after your code,  
   ' since now it is very easy to switch it off! :-)  
   SecurityManager.DisableOOMWarnings = False  
End Try  

Visual Basic 6 (VBA)

OlSecurityManager.DisableOOMWarnings = True  
On Error Goto Finally  
   ' ... any action with protected objects ...  
Finally:  
   OlSecurityManager.DisableOOMWarnings = False  

Delphi

OlSecurityManager.DisableOOMWarnings := True;  
try  
   // ... any action with protected objects ...  
finally  
   OlSecurityManager.DisableOOMWarnings := False;  
end;  

Outlook Security Manager is an in-process COM object that handles all
internal events of the Outlook E-mail Security Engine rather than "hacks" or
"hooks". Outlook Security Manager directly supports three platforms, .NET,
VCL and ActiveX (VB.NET, C#, C++ MFC/ATL/.NET, Visual Basic 6, Delphi, VBA,
Word MailMerge) and takes into account the platforms' peculiarities. Please
note all the editions are included in one license package. Fix Outlook
security problem programmatically with a line of code! Enjoy Outlook
development with no irritating popup warnings. You can order Outlook
Security Manager now, get it instantly and use Outlook objects without any
security troubles.

url:http://www.ureader.com/msg/1081800.aspx

How to prevent Outlook security warnings from appearing?
Need to remove security alerts? With Outlook Security Manager you can easily
bypass security settings in MS Outlook and turn off an alert, or a pop-up
message with just one line of code! Unlike similar tools, Outlook Security
Manager doesn't transform OOM (Outlook Object Model) and CDO (Collaboration
Data Objects) calls to Extended MAPI calls and doesn't make development more
complicated by its own special objects. It just implements one object with
three properties that enable or disable security settings for Outlook
objects, CDO and Simple MAPI including MailMerge. These properties are
DisableOOMWarnings, DisableCDOWarnings and DisableSMAPIWarnings. Before
calling a protected object you just switch off Outlook security via the
corresponding property, and then you turn it on again. For example:

Visual Basic .NET

Dim SecurityManager As New AddinExpress.Outlook.SecurityManager  
SecurityManager.DisableOOMWarnings = True  
Try  
   ' ... any action with protected objects ...  
Finally  
   ' In any case please remember to turn on  
   ' Outlook Security after your code,  
   ' since now it is very easy to switch it off! :-)  
   SecurityManager.DisableOOMWarnings = False  
End Try  

Visual Basic 6 (VBA)

OlSecurityManager.DisableOOMWarnings = True  
On Error Goto Finally  
   ' ... any action with protected objects ...  
Finally:  
   OlSecurityManager.DisableOOMWarnings = False  

Delphi

OlSecurityManager.DisableOOMWarnings := True;  
try  
   // ... any action with protected objects ...  
finally  
   OlSecurityManager.DisableOOMWarnings := False;  
end;  

Outlook Security Manager is an in-process COM object that handles all
internal events of the Outlook E-mail Security Engine rather than "hacks" or
"hooks". Outlook Security Manager directly supports three platforms, .NET,
VCL and ActiveX (VB.NET, C#, C++ MFC/ATL/.NET, Visual Basic 6, Delphi, VBA,
Word MailMerge) and takes into account the platforms' peculiarities. Please
note all the editions are included in one license package. Fix Outlook
security problem programmatically with a line of code! Enjoy Outlook
development with no irritating popup warnings. You can order Outlook
Security Manager now, get it instantly and use Outlook objects without any
security troubles.

url:http://www.ureader.com/msg/1081800.aspx