Foremost, follow the instructions in the communications you receive.
If the communication is merely notice of what you will receive, wait to receive it. If, in contrast, the communication directs you to submit certain information or documentation, make a concerted effort to timely submit that.
Others probably have more direct personal experience with email requests and can more clearly address this. My impression is that if there is notice in eCas of a communication, wait for the substantive communication to respond. Otherwise, email is typically in lieu of paper mail, so the PR needs to respond to the email itself as if it was paper mail. In any case, however, it is what is stated in the communication YOU RECEIVED that matters. Which is to say, regardless what anyone reports they received, you need to respond according to what it says in the communication YOU RECEIVED.
If the language in the communication is not the language which you are most accustomed to using, or you are otherwise not sure what the instructions are, it would be prudent to have someone help you read and understand the instructions.
Nature of Process; Does NOT Appear to be SR:
This does NOT appear to be notice of a referral for Secondary Review. Rather, it appears to be a request for additional information and documentation for the purposes of calculating your compliance with the PR Residency Obligation.
While questions related to PR RO compliance appear to trigger many of the referrals for SR, the nature and focus of SR goes beyond the scope of assessing PR RO compliance.
In contrast, if there is a particular concern about PR RO compliance on the face of the application for a new card, IRCC will typically request additional information and documentation, and proceed to calculate compliance.
(There is a tendency in the forum to conflate what can trigger a referral to SR with what SR involves. PR RO compliance questions can indeed trigger SR but again SR tends to be about other issues. Note, for one example, among others, if IRCC has the impression the PR is residing outside Canada, that appears to also trigger SR and can lead to no action on the PRC application unless and until there is indication the PR has returned to Canada. )
Timeline:
There is no promise, no assurance, no indication even, that IRCC will promptly assess the case soon after receiving requested documents. So NO, the deadline for submitting documents does NOT mean that they will review the documents soon, or at least it does not mean that IRCC will make a decision soon. IRCC might. Might not.
