Can Microsoft 365 add a signature to every email automatically?

Yes. With a mail flow rule in Exchange Online, the server adds a signature under every outgoing email, with the name, job title and phone number from Entra ID. No extra licence is needed.

Why can’t I see that signature while typing?

A mail flow rule only adds the signature on the server, after you click Send. That is why you do not see it in the window you are writing in, nor in Sent Items.

Does a central signature work on phones too?

A mail flow rule does, because the server adds it regardless of the device you send from. A signature you set yourself in Outlook usually has to be set up separately in the Outlook app on your phone.

Can I put a logo in the signature?

With a mail flow rule, only as a link to an image on the internet, and many recipients only see it after a click. For a signature with a logo that looks right for everyone, a signature tool that connects to Microsoft 365 is the better choice.

Where do the details in the signature come from?

From the user account in Microsoft Entra ID: display name, job title, department and phone numbers. If those are wrong, the wrong number ends up under your emails. So correct those details first.

A different signature for every colleague: how an SME should manage email signatures centrally in Microsoft 365

Put emails from five colleagues side by side and you will often see five different signatures. One still has the old logo, one a phone number that stopped working a year ago, one a quote in an eye-catching font and one nothing at all. On the phone it says ‘Sent from my iPhone’. Customers see all of it. A signature looks like a detail, but it is the business card under every email your company sends.

Why signatures drift apart

In Outlook, every member of staff creates their own signature. That is how it has always worked, and that is why signatures drift apart. Someone copies a colleague’s signature and changes the name, but forgets the mobile number. With a new logo or a new address, everyone has to change something themselves, and by no means everyone does. On the phone, the Outlook app often has a separate default signature. And new starters begin with no signature at all, until someone remembers.

That is more than a cosmetic problem. A customer calls a number that no longer exists. A signature without company details looks less trustworthy. And if your own emails keep looking different, a fake email pretending to be your company stands out less.

Step 1: get the details in Entra ID right

Every central approach takes the name, job title, department and phone numbers from the user account in Microsoft Entra ID. If those details are wrong, everyone will soon have a neatly formatted wrong number under their emails. So first check each person’s display name, job title, department, office number and mobile number. Agree who keeps them up to date, for example when people join or leave or change roles. The address book in Outlook and Teams will then be correct too.

Three ways to manage it centrally

A standard signature in Outlook. You create one standard and ask everyone to adopt it. Recent versions of Outlook store the signature in the mailbox, so it follows people to other computers and Outlook on the web. It is still manual work per person, and nobody checks whether the signature is correct.
A mail flow rule in Exchange Online. A rule adds text on the server under every outgoing email to external recipients. Using fields such as the name, job title and phone number from Entra ID, everyone automatically gets their own details. This works for every email, including from phones, and needs no extra licence.
A signature tool that connects to Microsoft 365. Specialist third-party tools manage signatures centrally, with a design per department, logo, banners and often a preview in Outlook while typing. That costs a subscription per user, but gives the neatest result.

The limitations of a mail flow rule

A mail flow rule is quick to set up, but it has a few drawbacks. The signature is only added on the server. So the person sending does not see it while writing, nor in Sent Items. In a reply, the signature ends up at the bottom of the whole conversation instead of directly under the new message. An exception in the rule does stop it being added again with every reply. A logo is only possible as a link to an image on the internet, and many email programs only show such an image if the recipient chooses to. If a field such as the mobile number is empty, you are left with a blank line or a stray label. So keep the signature simple if you choose this route.

What a good signature contains

Keep it short: name, job title, company name, one or two phone numbers and the website. Many companies also include their address and company registration number. Leave out quotes, multiple logos and large images; they make emails heavy and often arrive at the recipient as attachments. Never put details in a signature that a fraudster could use to redirect payments, such as a bank account number described as ‘our new number’. If you use a shared mailbox, such as info@ or invoices@, set up a fixed department signature for that mailbox too. And record the chosen setup in your IT documentation, so someone else can change it later.

How Floor ICT handles this

Floor ICT looks with you at what the signatures look like today and what result you want. We correct the user details in Entra ID and agree who keeps them up to date. We then choose the approach together: a mail flow rule for a simple text signature, or a signature tool if you want a logo and a design per department. We set it up, test it in Outlook, Outlook on the web and on phones, and clear out the old signatures so emails do not end up with two. As part of our managed service, we update the signature whenever you get a new logo, address or new member of staff.

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