10 Email Signature Mistakes That Make You Look Unprofessional
The most common signature errors we see — and the quick fix for each one.
By Editorial Team, Editors, SignatureCraft · Updated 2026-10-12 · 6 min
Ten common email signature mistakes — from oversized images to broken spacing in Outlook — and how to fix each one in minutes.
Mistakes in what you include
Too much information. Two phone numbers, a fax, a street address, five social icons and a disclaimer turn a signature into a footer. Fix: keep the details people actually use to reach you.
A generic free email address. A professional title next to an address on a free webmail domain undercuts the whole signature. Fix: an address on your own domain, which costs little more than a coffee each month.
An outdated title or number. Nothing says “not paying attention” like a job you left last year. Fix: put a reminder in your calendar to review your signature twice a year.
Mistakes in how it looks
A blurry or pixelated logo. Fix: export your logo at twice the size it is shown, so it stays crisp on high-resolution screens.
Too many colours. Fix: one main colour for your name, one accent for dividers or links, and grey for everything else.
A signature that is one big image. Images get blocked, cannot be clicked or copied, and are invisible to screen readers. Fix: real text, with images only for the logo and photo.
Custom fonts. Fix: web-safe fonts with a backup listed, so the signature looks the same for everyone.
Mistakes that only show up in other inboxes
Spacing that doubles in Outlook. Paragraph gaps and relative line heights get reinterpreted. Fix: line breaks and fixed pixel line heights — the style guide has copy-ready code.
Phone numbers turned blue on iPhones. Apple Mail auto-links numbers it finds. Fix: link the number yourself so you control the colour.
A logo that disappears in dark mode. Fix: give dark logos a light outline or use a version with a solid background.
You can check for most of these at once with our free Signature Grader, or preview your signature in Gmail, Outlook, Apple Mail and dark mode right inside the editor before exporting.
Put these tips into practice
The SignatureCraft editorial team writes about email tooling, deliverability and the small design details that quietly shape how professional we look online.