Controlling portlet availability via client headers

Question

I have a portlet that I want users to only be able to see if specific HTTP headers are present in the request to the portal (these will be added via the proxy en-route).
My initial thought was to implement this as a Login PEI - set a user attribute on login based on the header, and use dynamic group membership with that group having permission on the portlet. I've implemented the code no problem, however I've only just twigged that this won't work though, as:
1. dynamic group memberships are updated asynchronously via an Automation task
2. I need it to be specific to that user session - a user can be logged in from more than 1 location at once, so I need that user's particular browser session to reflect the location they're logging in from (so the data can't be permanently stored against the user object).
I know that I can customise the portlet code itself based on session data, however I need to specifically either show or hide (and prevent the user from seeing) a portlet in the "add portlets" page when they're not coming in from the specific location.
Does anyone know of a way that I can make a portlet available based on something that I can set at a session level?
Cheers
darren

Answer 1

In this case, the SMTP domain is the same as the AD domain.  If the wrong domain were configured then the connection would never work, as opposed to sometimes work.
RunspaceId            : abb30c12-c578-4770-987f-41fe6206a463
ForestName            : adatum.local
UserName              : adatum\availtest
UseServiceAccount     : False
AccessMethod          : OrgWideFB
ProxyUrl              :
TargetAutodiscoverEpr :
ParentPathId          : CN=Availability Configuration
AdminDisplayName      :
ExchangeVersion       : 0.1 (8.0.535.0)
Name                  : adatum.local
DistinguishedName     : CN=adatum.local,CN=Availability Configuration,CN=Wayport,CN=Microsoft
                        Exchange,CN=Services,CN=Configuration,DC=contoso,DC=local
Identity              : adatum.local
Guid                  : 3e0ebc2c-0ebc-4be8-83d2-077746180d66
ObjectCategory        : contoso.local/Configuration/Schema/ms-Exch-Availability-Address-Space
ObjectClass           : {top, msExchAvailabilityAddressSpace}
WhenChanged           : 4/15/2014 12:33:53 PM
WhenCreated           : 4/15/2014 12:33:35 PM
WhenChangedUTC        : 4/15/2014 5:33:53 PM
WhenCreatedUTC        : 4/15/2014 5:33:35 PM
OrganizationId        :
OriginatingServer     : dc01.contoso.local
IsValid               : True
ObjectState           : Unchanged