A PS line works on a quirk of how people skim: someone who scans the first line, jumps straight to the sign-off, and never reads the middle of the email will often still catch a line sitting just below the signature, because it's visually separated and looks like an afterthought worth a glance. That makes it a genuinely useful spot for the one thing you'd most want a skimmer to see — but only if it's used for something that earns the extra attention.
Email readers, especially on mobile, don't read cold emails top to bottom the way the sender wrote them. A subject line and a first sentence decide whether the email gets opened at all; after that, a lot of recipients skip to the end to see who sent it and what they want, particularly if the body looks long. A short line set apart after the signature sits exactly where that skim lands, which is why it tends to get disproportionate attention relative to its length.
The line earns its place when it does one of a few specific jobs the body copy can't do as efficiently:
What doesn't belong in a PS line: a repeat of the main CTA in slightly different words, a generic urgency line ("don't miss out"), or a second unrelated pitch. Each of those either wastes the attention the PS line earns or actively undercuts the read that this is a considered, human message.
If the email is already short — under roughly 80 words — a PS line can end up adding more length than the body itself, which defeats the point of writing a short email in the first place. It's also worth skipping if there's nothing genuinely worth adding; a PS line with generic, low-value content ("PS — looking forward to hearing from you!") reads as filler and can flag the email as templated rather than considered, which works against the purpose of including one at all.
It doesn't guarantee a reply, but it does reliably get read, because skimmers who skip the body often still catch a short line set apart below the signature — which makes it a good spot for the single most persuasive point, not a required element of every email.
A concrete proof point, an alternate lower-commitment CTA, or a genuinely specific personal detail — something that earns the extra attention a PS line gets, rather than repeating the main ask.
No — a short email under about 80 words often doesn't need one, and a PS line with nothing genuinely useful to add reads as filler rather than a considered addition.
It's usually better not to. Repeating the same ask in different words wastes the attention a PS line earns; using it for something the body didn't already cover works better.
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Written by
Scott Holmes
AI systems consultant based in Barrie, Ontario. Founder of Pinnacle Tech Projects. Has tested PS line placement and content across cold email campaigns.
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