Send a few introduction emails, now my email comes up as spam

So I sent a single introductory email to about 100 businesses relevant to the service I am selling. It went well and I got some good business. I did the same thing again with some other relevant businesses I found but I didn't get the same response. I sent the same email to my personal gmail as a test account and it went to the spam folder.

Is there any way to reverse this? It's very disheartening to send a single nice introduction email and have my business be potentially ruined because of it.

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