I wonder why should I manually create the url for the collector map? why should I take the web map id, copy it to the url template, and copy the full url to my mail? why can't the web map item page can have a button saying: create a collector url?
I have another problem with the Android version. While in iPhone I can open the url and collect features, my Android device does not recognize the same url and the application can't open.
Getting maps on the collector app is something that will be improved in the next update. Some android email clients dont support the URI schema links properly, I would encourage you to send a feature request to the app your using for your mail if possible. The other workflow is just using the http:// link for the item details page of the map you're trying to share, it has a few extra steps but is much better supported. As I mentioned though in the next update both these options will be secondary workflows and we will have a more streamlined in app experience for getting your collector maps.