Cold Mailing is an important and effective tool in acquiring opportunities in the research space. But one must ensure that their practices do not lead to spam.
Your approach to finding a position can look like this in no particular order (this is not conclusive and opinions may differ)
Cold Mailing is a process that a lot of us are familiar within the small circles that are aiming for thesis. Its the bread and butter of trying to find opportunities. You will see people with different mileages but it is not rare for most applicants to hit 100-200 mails consistently.
While it is a very versatile tool, it can also be abused by people to send out mails with little to no thought - finally leading to a vicious cycle.
When people spam the inboxes of as many profs as possible. Two things happen
either way, the pool of responding professors shrinks massively every year. This continues and it becomes increasingly hard for students to find research experience abroad - hence people mail even harder and the cycle continues. All in the hopes of securing an international offer.
While we understand that research in our college covers only a subset of topics. It is important to understand that in-country theses have wrongly been classified as inadequate and a "last resort" when they are definitely not so. Your college and the surrounding external places in India should be as important as the foreign component of your mailing list and be treated the same way without any bias.