How have potential recommenders rejected you?

[Chumado]

I'm asking because I seem to have spotted a trend and was curious to know if that's standard. 

I have been out of undergrad for almost 5 years so I absolutely understand professors not wanting to recommend me for grad school. I had good professional recommendations but I wanted an academic one so I said what the hell and asked 3 undergrad professors. One was glad to do it. The other 2, however, just never replied at all. Not even to say "I don't know you, sir." They knew me well, by the way. 

Is this the system in place for rejections? 

[fuzzylogician]

Depending on when you emailed and what email address you used, it might be the case that you haven't given it long enough and that it's simply a busy time of year (end of semester, exams, holiday-related travel, vacation) or that the email address seemed unfamiliar if it's not university-affiliated. This is a way some people handle emails they'd prefer not to answer, but I at least usually prefer to assume the best of people until proven otherwise, so if this isn't urgent I'd just wait until after the New Year and try again. Now is not a good time to expect people to be tending to their email. 

For what it's worth, when I decline such requests, I reply to say "I'm sorry but I don't think I can write you a strong letter of reference, I suggest that you find someone who knows you better". (These would be students who attended a 150-student lecture I taught, where I had no personal contact with basically anyone who didn't attend office hours, so I couldn't say anything beyond "Stu was registered for Class and earned Grade." I wouldn't even know if they were ever physically in the lecture hall, so that would be a very weak letter that wouldn't help anyone). It takes me 2 minutes to do this, and I'm sure it relieves some anxiety for the student, even if it's not what they were hoping to hear. 

[Chumado]

I sent the emails asking for the LOR back in September, almost 2 months before they would receive an email from the school inviting them to do it online. 

It is true that my email address was unknown and it might've been considered spam. I sent the email again but that wouldn't have helped, in fact, I think that's more the reason why a filter would consider me spam. 

One of the two professors is a big shot in a top college in London now, so I can see him clicking on ignore the minute he saw my heading. The other, is the sweetest person I've met so it surprised me from her. There's no way my emails didn't get to her since she works at the same school as the professor that did agree to do it so I'm sure their email server works the same and it did not send me to spam. 

I went to a big state school but majored in philosophy so that department was small. All the majors knew each other and I had very close relationships with the small faculty department. 

I would also like to think the best of people and like I said, I understand them not wanting to write the letter. A quick email telling me no would've been great. I can't be absolutely certain they, in fact, received the emails so I guess this will forever remain an unsolved mystery. 

[Kaede]

Did you ever follow up with them? Sometimes emails get buried in inboxes because professors are busy. A simple "I just wanted to check if you received my previous email" should suffice.

[kbui]

When I was in my first semester of undergrad, I asked my biology professor to write me a recommendation letter for this student research program, in person. She came out and directly told me, "I can write you a letter, but it will not be very good." I was devastated. Now looking back at it, it wasn't that big a deal. But I learned my lesson and since then have only asked professors that have known me well to be letter writers.

[Adelaide9216]

I also had a prof refusing to do an recommendation for me. I had an A in his class, and he remembers me, that was just one or two years ago I have a feeling he doesn't like me, but I will never know why. First time this happens to me.