Write a reminder about a possible undergraduate project I am currently doing some research for choosing a topic for my M.Sc. thesis. 

A week ago I sent an email to an external professor (I mean, not one in my University) asking about whether we could discuss about the topic I chose. The mail was (I believe) properly structured - not spammy and personally tailored on the prof, citing some works on the topic I took a look on, explaining my motivations on why I would like to study this topic, maybe a bit lengthy but not that much and divided in paragraphs - yet I had no answer.

For what I know it seems that this is not necessarily a "no" and a common suggestion is to write a reminder. 

Now, I would really like to work on this topic and taking contact with this professor would be a great chance for me, especially in order to continue my studies with a PhD. At the same time, this professor is quite important and maybe he just doesn't care too much about a M.Sc. thesis, so I was thinking to write a reminder asking, in short, if he could send me the contact of one of his PhD/postdoc students that may be interested in helping me with my work.

My question is: is this considered a bad etiquette? writing first to a prof and then rolling back to one of his students...may sound like I underestimated his position or I am just not motivated enough. 
In case, how could I structure the message? It seems to me that "if you are too busy" is a bad way to start (sounds like I don't know whether the professor has anything to do or that he could be doing nothing). Also "I know you are very busy but..." sounds bad (but what? but I don't care? but I think it is more important to stop and talk with me?). So what could be a polite way to go for it?
I'm not in the best position to advise you, but, perhaps, he/she hasn't answered you back, because he/she was busy to do so.

Thus, you definitely should e-mail back. Quoting a professor, maybe something like this:

"My e-mail server has been acting up lately, so I'm not sure whether my previous message was delivered properly; here it is again, just in case. Thank you!"

Read the following before:


Email Writing Tips
Read This Before Cold-Emailing Me
Examples of Good and Bad Cold Emails


Best of luck!