i had a DM on my ECAS a few weeks back, around June beginning, at that time my wife also received the approval email.
however i am yet to receive any email for the SA approval, i also have nt received any correspondence for the landing interview.
Does this time line looks normal, been a month since DM.
So, it can happen. Check ECAS for a line on the Sponsor side that says they sent you correspondence regarding the decision.
That said, it's not really necessary to get it. Understood you want to read it for your own peace of mind. However, this might placate you:
In the Family Class, you have to have a sponsor. If the sponsor is not approved, they will not render a positive decision (as the person is not a member of the Family Class by lacking a sponsor.
We have seen this before, where SA didn't come. Simple fact is, it's pretty hard not to be approved to sponsor. As long as the sponsor is:
- a Canadian or a PR
- not in jail or prison
- has not committed a violent crime against family (domestic)
- does not receive social assistance for anything other than a recognized disability
- isn't currently sponsoring someone else (remember the sponsorship period is 36 months)
That's it. If all those "tests" pass, the sponsor can sponsor. End of story.
With respect to the Landing Interview, what office will you be landing at? Are you in Quebec? Toronto (or GTA)? Those offices are a little slower than others...
You don't have to take my word for it. If you don't believe me, call 888-242-2100 and ask for a status update.
( Who am i kidding, i finished all my work for the week and i don't even know why i'm even in the office today...or right..day off denied #bitter) 
