Chances are it can't. Virtually all anti-spam software only provides whitelisting based on sender IP or email address.
Well, what do you do if you can't readily anticipate the IP address of an important email? Not much you can do with most email security solutions, but to hope it doesn't get blocked - or worse yet rejected.
Some examples where contextual white listing capability is critical are:
These are just a few examples of where you are not able to identify the sender with an IP or email address, but need to be sure that you receive the email.
Most anti spam software on the market is completely incapable of handling these situations.
What is required is anti spam functionality that is able to white list (always pass) email, based on the content of the email itself. This capability is called contextual white listing.
THE SOLUTION IS: EMP Enterprise Anti spam - which can whitelist based on any email content![]()
At the heart of EMP's architecture, is a contextual message routing engine, which permits EMP to route (Pass, Delete, Reject, Reroute) email based on specific content of an email. This content can be within the email header, email body or tail of the email.

EMP 7 Enterprise Anti spam (Windows)| # | Name | Size | Added On | Last Updated On | Downloaded |
|---|---|---|---|---|---|
| 1 | EMP 7.0 Windows (x86) (View) | 79.42 MB | Mar 22, 2009 | Jun 27, 2011 | 1189 times |
| 2 | EMP 7.0 Windows (x64) (View) | 79.8 MB | Mar 22, 2009 | Jun 27, 2011 | 1028 times |

EMP 7 Enterprise Anti spam (Linux / UNIX)| # | Name | Size | Added On | Last Updated On | Downloaded |
|---|---|---|---|---|---|
| 1 | EMP 7.0 Linux(X64) (View) | 90.17 MB | Mar 22, 2009 | Jun 27, 2011 | 520 times |
| 2 | EMP 7.0 Linux (View) | 80.89 MB | Mar 22, 2009 | Jun 27, 2011 | 515 times |

EMP 7 Enterprise Anti spam (Mac OS X)| # | Name | Size | Added On | Last Updated On | Downloaded |
|---|---|---|---|---|---|
| 1 | EMP 7 Mac OS X (View) | 62.58 MB | Mar 22, 2009 | Jun 27, 2011 | 674 times |