Smtp plugin to send e-mail notification

Hello everyone. I have an issue, i host my website on vps server and email account on the same server, now I got spam in my account that send so much spam (15 000)that the vps shot down my mailing service on my vps. NOw I could start over again but I will face the same problem again. Now I though that I should host my e-mail on gmail apps or outlook. But I have a problem event if I use a gmail(new e-mail)it doesn’t work, so I though using smpt plugin in the hope it would send not from php but smpt. Does this process work? I don’t know exactly how wordpress handle e-mail sending. Anybody have idea that could work?