Gmail SMTP caps at 2000/day on Google Workspace which sounds like a lot until you realize one spam complaint on Workspace can flag your entire organization. Every domain under that Workspace account gets tainted.
SES is great for transactional email but they monitor content closely. Cold outreach through SES will get you suspended quickly unless you have explicit opt-in for every recipient.
For cold email specifically, dedicated SMTP on a VPS you control is the only setup where you fully own your reputation. The tradeoff is you need to handle authentication yourself — SPF, DKIM, DMARC, rDNS, certificate management, milter configuration. Most people mess up at least one of these and wonder why they're landing in spam with a "proper setup."
The most common mistake I see: running OpenDKIM alongside a content filter like Rspamd or SpamAssassin without getting the milter execution order right. If your content filter runs after DKIM signs the message, it modifies headers and breaks the signature. Gmail silently rejects these. Check your smtpd_milters line in Postfix — signing must happen last.
