Contacting professors (from abroad)

[Joe VL]

Hi people,

I am not getting many replies from professors I´m contacting regarding prospective MSc research.

1) Maybe is because I´m writing from abroad and my IP gets recognized as spam and doesn't get to their main emailbox?

2) Perhaps it´s because I´m writing from a @yahoo.com and not from a professional email?

3) Or maybe it´s because I´m sending emails to, like, three professors at a time, from the same department, and only changing/tweaking the content a little bit each time?