Could it be a language issue? I mean, your dynamic properties are defined for language x but the subscription is actually triggered for a different language y (where the properties are undefined)? Or are they redefined below the subscription root (unlikely, but I have to ask)? I'm pretty sure the property is actually read from the page sent rather than the subscription root.
It turns out to be a user error, I think. I thought I had checked everything, but now I find out that on some of the subscription roots the EPSUBSCRIBE-EXCLUDE property was set to true. And as far as I know those were the pages where the newly added pages were published underneath.
The method that fetches the subscription root checks for that property when it gets it and if it's set, it doesn't fetch the page.
I'm not 100% sure this solves it, but I did get a subscription mail that had gotten the right text this morning 8which is how I found the error), so I hope that's the case.
The embarassing part is that I did check this property on some of the pages (because I saw in the code it shouldn't be set), but apparently not on the ones that sent out erraneous error messages.
I am working on a site just upgraded from EPiServer 4 to 6 and I'm having problems with the subscription module.
The subscription mails go out, but the properties that are used to override the default format doesn't take, instead the mails go out with the default values.
I know that the way subscriptions are handled have changed and I have adapted the settings. I've added the properties SubscriptionMailFrom, SubscriptionMailSubject, SubscriptionMailBody and SubscriptionMailReadmore as dynamic properties and assigned them values on the start page. The subscription root pages are all direct children of the startpage and inherits those values (as they should) in edit mode.
I'm starting to run out of ideas to try, so I'm wondering if anyone has a sggestion to what could be wrong.