AI email comparison
OpenAI (ChatGPT) vs Grok (xAI) for Email Drafting
Grok's edge is live X context and a looser default voice; ChatGPT's edge is a mature prompt ecosystem and stronger formal-email track record. For client-facing mail, Grok usually needs more instruction to sound professional. Neither integrates with Gmail or Outlook on its own.
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
Grok (xAI)
Elon Musk's xAI model. Strong technical capabilities and current events access via X integration. Still maturing for professional email use cases.
Grok is the newest professional-email contender here, and it shows: its main differentiator is live access to X (Twitter) posts and trends, which matters for social-media-adjacent writing but has little bearing on drafting a client email. It ships with a looser 'fun mode' default voice alongside a more measured standard mode, both accessible via the standalone Grok app or bundled into X Premium+ without a separate subscription. Grok 3 closed much of the raw capability gap with GPT-4o and Claude on general instruction-following, but the surrounding ecosystem, prompt libraries, integrations, third-party tool support, is still thin compared to OpenAI's or Anthropic's. For email specifically, there's no Gmail or Outlook integration, no memory across sessions, and the default tone requires deliberate correction toward formality for anything client-facing.
Strengths for email
- Real-time information access via X (Twitter) integration
- Strong at casual, direct prose
- Available bundled with X Premium
- Grok 3 shows significant capability improvements
Weaknesses for email
- Limited professional email track record vs. OpenAI/Anthropic
- No Gmail or Outlook integration
- Community prompt resources thin compared to ChatGPT ecosystem
- Casual default tone requires heavy instruction for formal email
Pricing: Bundled with X Premium (~$8-16/mo)
Best for: X/Twitter power users who already pay for Premium and want a bundled AI
Head-to-head for email
Verdict for email drafting
Use Grok if you already pay for X Premium and mostly write casual, current-events-adjacent notes. Use OpenAI for the bulk of professional email. For either model, tab-switching and cold starts remain the real bottleneck.
Using OpenAI (ChatGPT) or Grok (xAI) inside your inbox
With ForthWrite BYOK you can point warm or formal threads at OpenAI and keep a cheaper or more casual route on another provider when it fits. Drafting stays in Gmail or Outlook Web, with a shared voice profile across accounts.
Both OpenAI (ChatGPT) and Grok (xAI) 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.