Outlook email signature generator
Outlook on Windows renders mail with the Word engine, not a browser engine, so half of ordinary CSS does nothing there. The signature below is built from a table with inline styles for exactly that reason — it looks the same in the desktop app, in Outlook on the web and on a phone.
No add-in, no account, no upload. Your details are assembled into markup inside this tab and reach Outlook only when you paste them there yourself.
Where the signature setting lives
There are three different Outlooks in common use, and each hides the setting somewhere else. Press Copy signature above first, then follow whichever of these matches what is on your screen.
Outlook on the web
Open the gear icon at the top right, then Mail → Compose and reply. Paste into the Email signature box, give the signature a name, then use the two dropdowns underneath to choose which signature applies to new messages and which to replies and forwards. Press Save. Skipping the dropdowns is the usual reason a signature exists but never appears.
New Outlook for Windows and Mac
Same layout as the web version, because it is largely the same application in a desktop window: Settings → Accounts → Signatures, or Settings → Mail → Compose and reply depending on the build. Signatures set here are stored with your Microsoft 365 mailbox rather than on the machine, so they show up in Outlook on the web too, on any computer you sign in from.
Classic Outlook for Windows
File → Options → Mail → Signatures…, or from any compose window, the Message tab → Signature → Signatures…. Click New, name it, paste into the edit box, and set the New messages and Replies/forwards dropdowns on the right. These signatures are stored on that one PC unless your organisation has cloud signatures switched on.
Signatures belong to accounts, not to you
In the classic desktop Signatures dialogue, the panel on the right begins with an E-mail account dropdown. Everything below it — the default for new messages, the default for replies — applies to that account alone. Add a second mailbox, a shared mailbox or a delegated account and it starts with no signature at all, which is why mail sent "on behalf of" a team address so often goes out bare. Set each account explicitly.
The same is true in Outlook on the web: settings live in the mailbox, so a shared mailbox opened in a second tab has its own, separate configuration.
The .htm files in %appdata%\Microsoft\Signatures
Classic Outlook for Windows does not store signatures in a database. Every signature you create becomes three files in %appdata%\Microsoft\Signatures — paste that string into the Explorer address bar and it resolves. You will find Name.htm for HTML mail, Name.rtf for rich text and Name.txt for plain text, plus a Name_files folder if any images are involved.
Two things follow from that. First, moving to a new machine is a folder copy, not a re-typing exercise: close Outlook, copy the folder across, reopen and reassign the defaults. Second, when Outlook's own editor has mangled the spacing and will not let you fix it, you can edit the .htm file in a text editor and paste the source from Copy HTML above straight into it. Close Outlook before you edit — it rewrites the file when it exits, and will overwrite your changes.
The rendering quirks this markup works around
Since Outlook 2007, the Windows desktop client has rendered incoming HTML with Microsoft Word's engine rather than a browser engine. Word has no support for float, flexbox, grid, background-image, max-width or CSS positioning, and it ignores anything in an external stylesheet. Layout that depends on any of those collapses into a single unstyled column. A table with widths and padding declared on the cells is the only construct that behaves predictably, which is what this generator emits.
Spacing is the second trap. Word applies its own paragraph spacing to <p> elements and collapses adjacent margins, so a signature built from paragraphs comes out with either gaps you did not ask for or lines jammed together. Padding on a table cell is not subject to margin collapsing, so it survives. Word also converts pixels to points at three-quarter scale, so odd pixel values round unpredictably — this page sticks to sizes that divide cleanly.
Images are the third. Windows display scaling above 100% enlarges images in Outlook, so a logo authored at 200 pixels wide appears at 250 on a 125% display and looks soft, and Outlook frequently ignores CSS width on an <img> in favour of the file's own dimensions. Combined with the fact that remote images are blocked until the reader clicks to allow them, that is enough reason to leave logos out entirely. A coloured rule and a coloured company name carry the brand at no risk.
Questions people ask
Why is there extra space between the lines of my signature in Outlook?
Word's paragraph styling is being applied to your markup. If the signature is built from paragraphs or line breaks, Outlook adds its default space-after to each one, and there is no way to remove it from inside the signature editor. Rebuilding the block as table rows with explicit cell padding — which is what Copy signature gives you — removes the problem at source. If you are repairing an existing signature, editing the .htm file directly is faster than fighting the editor.
Where does Outlook store signatures on Windows?
In %appdata%\Microsoft\Signatures, as one .htm, one .rtf and one .txt file per signature, plus a folder of assets if images are used. New Outlook and Microsoft 365 cloud signatures are stored with the mailbox instead and sync between devices. If you have both, the local files belong to classic Outlook only, and editing them will not change what new Outlook sends.
Why is my company logo blurry in Outlook?
Windows display scaling. At 125% or 150%, Outlook draws images at that scale rather than at their natural pixel size, so a logo sized for 96 DPI is stretched and softened. The usual workaround is to supply an image at twice the intended size and set explicit width and height attributes, but that trades one problem for a heavier signature that most clients block on first view. This tool sidesteps it by not using images at all.
Can I make the signature appear on replies as well as new mail?
Yes, and it is a separate setting from the one for new messages. In classic Outlook the Replies/forwards dropdown sits directly under New messages in the Signatures dialogue; in Outlook on the web and new Outlook, the two dropdowns are under the signature editor. Many people deliberately use the full signature for new mail and a shorter one for replies, so a long thread does not accumulate the same contact block a dozen times.