Suppose I (a senior postdoc in Europe) write an email to another not-student scientist (a postdoc or a professor also in Europe) that does not know me nor directly nor by publications. I am either asking about writing a common project or about an open position or some scientific question related to their work.
I see many disadvantages in using institutional emails so usually I use a private Gmail one. However most often people never answer (and I am pretty sure my emails are not bad enough to offend anyone or boring enough to generate zero interest). I got used to think that people are just too lazy/too overwhelmed with many things to answer every random guy with a PhD with at least one sentence.
But recently I started to work in a place where people are extremely paranoid about internet security to the point that they mark all incoming emails from other institutions (let along free mailservers) in a special way. So I started to wonder: what if many of my emails (that were most often sent to institutional addresses, since usually they are the ones publicly available) were lost in spam or even deleted automatically due to paranoia of people setting mail server configuration?
So what is your experience? Do you think my problem getting replies from people can be related to me using my private email? Or it is just yet another one harsh reality of Academia one has to accept?