How long should a subject line be?

The "spam words to avoid" lists you see online are largely outdated myths. Modern spam filters don't block emails for saying "free," "sale," "discount," or "limited time." If they did, every retailer would be in spam. Context determines filtering, not vocabulary.

What matters: sender reputation (trusted senders can say anything), recipient engagement (if people open and click, filters learn your mail is wanted), and overall composition (suspicious patterns across the full email, not individual words). A bank can write "free checking account" without issue because banks legitimately offer free checking accounts.

Use the words your message needs. If you're offering a sale, say "sale." If something is free, say "free." Don't contort your language to avoid imaginary triggers. Focus on clarity, honesty, and relevance. The only subject line "words" to actually avoid are deceptive ones—fake RE:/FWD:, misleading claims, bait-and-switch tactics. Those hurt you not because of vocabulary but because they're dishonest.