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My "guess" is as follows. The internet is, to a significant degree, controlled by trolls and shills who seek to shut down communications that they find threatening to their efforts toward a monopoly on power and control. Many find political opinions to be extremely distasteful. Especially if those opinions differ from their own.
However....it is what it is. One would think that a different email would not "trip" their anti-spam filters. Spam.....huh...what a tactic to shut down dissent. Already tried a different username to no avail. It would be easier for Ingsoc to drop an email address that has fallen out of favor. So that is likely what Ingsoc has chosen.
Or perhaps the use of a VPN triggered this? This is a brand new phenomenon.