What makes a cold email subject line work
It looks like something a colleague would send. That means short, lowercase-friendly, about the recipient rather than you, and with no sales words. The best performing subjects in cold email are often two to four words: the company name, a project, a mutual connection, a city.
Why 40 characters
Most phone mail apps show 35 to 45 characters of a subject before cutting it. Desktop shows more, but most cold email is first seen on a phone. Put the important word first.
Never fake a reply
"Re:" on a first email gets opened once. Then the recipient realises they were tricked, and the report-spam rate on that domain climbs. Spam complaints above 0.3% get a domain throttled by Gmail; the damage from one trick outlasts any open-rate bump.
Questions
How long should a cold email subject line be?
Under 40 characters so it survives a phone inbox. Two to four words usually performs best.
Should I use the person's name in the subject?
Rarely. First names in subjects are now a marketing pattern. Use their company, their project or something specific to them instead.
Do emoji in subject lines hurt cold email?
Yes for B2B cold email. They signal marketing. Save them for lists that opted in.
