Indicating work was performed as a student for alumni I have graduated with a master's and have maintained collaboration with my advisor to publish papers. I have a paper accepted in a rank A+ conference of my field.

My university e-mail address is still active but my advisor recommended I use my gmail address. I should be starting a PhD next year at the same institution so the address is likely to stay active. I put this university as affiliation since I did the work there.

Assuming I use the gmail address, should I add a footnote to my name saying "Work completed while an MSc student at institution" to explain the affiliation?

In acknowledgements, authors acknowledge grants for funding their work. Is it a place where an alumni can say he did the work as a student at the institution?

I've seen this done for papers published by students about work done during internships at companies while providing a university affiliation, such as "This work was completed while name was at company" but never have I seen this for alumni. Is it because it doesn't happen often, or would a footnote be perceived as pompous? 

Edit: A comment suggested this question possibly duplicates What affiliation to put on an academic paper for alumni authors? . This is not the case, I said in the question "I put this university as affiliation since I did the work there." . My question is about adding a footnote, or an acknowledgement, indicating I was a student there when I did the work. Question edited for clarity.
assuming I use the gmail address, should I add a footnote to my name saying "Work completed while an MSc student at institution" to justify the affiliation?


No, because you never need to justify right in the paper why your affiliation is indicated the way it is, or why you picked one e-mail address over another.


  I've seen this done for papers published by students about work done during internships at companies, such as "This work was completed while name was at company"


I can imagine the benefit here is to inform readers that company is not a likely place to get in touch with name any more. That can be useful information, but it is most likely not provided just as an explanation of why a particular e-mail address was chosen.