AI email comparison
OpenAI (ChatGPT) vs Gemini (Google) for Email Drafting
Gemini wins on convenience for Gmail users because Help me write sits inside compose. ChatGPT wins when you need a longer brief or a model outside Google's stack. Both still produce a generic default voice unless you invest heavily in instructions, and Gemini's suggestions often read like a polished template.
OpenAI (ChatGPT)
The most widely used AI assistant. Most ChatGPT-for-email power users start here, because it's the tool they're already tab-switching to.
OpenAI's consumer product is ChatGPT, but for email drafting the relevant distinction is between the free or Plus web app and the API. Plus subscribers get GPT-4o with custom instructions (a persistent system prompt you write once) and custom GPTs, which some professionals use as a rough style filter, though it requires re-pasting examples of your own writing and rarely holds up across a long thread. The API tier (GPT-4o, GPT-4o mini, and the o-series reasoning models) is what BYOK tools route through: pay per token, no chat history retained between calls unless the calling app manages it. ChatGPT Team and Enterprise add admin controls and a data-training opt-out, relevant for anyone drafting client-sensitive email. The practical gap for email specifically: ChatGPT has no concept of your Gmail or Outlook history, so every draft starts from whatever context you paste in, and default outputs lean toward a recognizable house style that recipients increasingly clock as AI-written.
Strengths for email
- Familiar interface; most users already have an account
- GPT-4o is strong at following complex style instructions
- Huge prompt-engineering community (r/ChatGPT, YouTube tutorials)
- Functions well as a catch-all AI for non-email tasks too
Weaknesses for email
- No persistent memory of your email style across sessions
- Requires manual copy-paste into Gmail or Outlook every time
- Generic outputs unless you write elaborate system prompts
- ChatGPT 'tells' (em-dashes, 'I hope this email finds you well') are widely detectable
Pricing: Free tier available; ChatGPT Plus ~$20/mo
Best for: General AI drafting when you want manual control over every word
Gemini (Google)
Google's AI assistant, natively integrated with Workspace. The most logical choice for Gmail users, though the integration is shallower than you'd hope.
Gemini's advantage for Gmail users is real integration, not just a chat window: the 'Help me write' panel appears directly inside Gmail's compose view, drafts inline, and can reference the current thread without copy-pasting anything. It runs on Gemini Flash for quick suggestions or Gemini Pro for longer, more nuanced drafts, both included with a Google One AI Premium subscription alongside Workspace-wide access to Docs, Sheets, and Drive context. The catch is that 'Help me write' output is templated: it produces competent, generic phrasing fast, but has no memory of how a specific user writes, and every draft resets to the same neutral default tone regardless of who the recipient is or the history between them. For teams already paying for Google Workspace, the zero-additional-setup integration is the draw; the trade-off is a ceiling on how personalized the output ever gets.
Strengths for email
- Native Gmail integration via Google Workspace add-on
- Access to Google Calendar and Drive context
- No separate subscription needed if you have Google One AI Premium
- Improving fast; Gemini 1.5 Pro is genuinely competitive
Weaknesses for email
- Smart Reply style is noticeably generic
- No persistent voice learning; every email starts cold
- Suggestions often feel like a polished template, not your voice
- Integration is one-click helpful but not voice-matched
Pricing: Free tier; Google One AI Premium ~$20/mo
Best for: Casual Gmail users who want quick suggestions without a separate tool
Head-to-head for email
Verdict for email drafting
Stay with Gemini if zero-setup inline drafts in Gmail are enough and you accept a ceiling on personalization. Choose OpenAI (or a BYOK tool that calls it) when you care more about following a detailed style guide than about native Workspace buttons.
Using OpenAI (ChatGPT) or Gemini (Google) inside your inbox
ForthWrite runs inside Gmail the way Gemini's panel does, but it learns your voice from sent history and can call OpenAI, Google, or seven other providers through BYOK. You keep the inbox surface and drop the generic Help me write ceiling.
Both OpenAI (ChatGPT) and Gemini (Google) still start cold in a chat tab: no memory of your sentence length, openers, or sign-offs unless you re-paste a system prompt every session. ForthWrite learns from sent mail and drafts in Gmail or Outlook Web so the model choice is a setting, not a workflow.
Draft with the model you prefer, in your voice
Free plan includes voice matching and 10 drafts/week. Standard and Pro unlock BYOK across 9 providers, including the ones on this page.