You rolled out the new signature on Monday. By Thursday, a sales rep had added a sunset photo and a Steve Jobs quote, and your CFO was still sending the 2022 version with the old office address.
Short answer: neither Microsoft 365 nor Google Workspace can lock an email signature. You can switch signatures off, or stamp a fixed footer on outgoing mail, and both only half-work. What works is putting the company signature back automatically, every day, whatever someone changed. That is what BulkSignature does.
A small problem that shows up in thousands of emails
One edited signature is not a crisis. The trouble is how many emails it rides on.
A phone number that stopped working last year goes out forty times a day. A job title from two promotions ago sits under a contract offer. The legal line your lawyer asked for is missing from half the sales team. And the brand your marketing people argued about for a month looks different in every inbox it lands in.
Then there is the person who has to fix it, which is you. You send the reminder. You send it again on Friday. One admin on Reddit's Office 365 forum put it this way: "you do have to constantly remind users not to append their own signature." A school IT admin, also on Reddit, described the other half: you push the right signature out, and some people "simply change it back later."
Nobody is being difficult on purpose. Someone liked their old one. Someone got a new laptop and typed a signature from memory. The result is the same.
Why you can't just lock it
It is the first thing every admin looks for, and the setting isn't there. Google says so in its own help: when an admin sets a signature for people, "they can edit it if they wish." Microsoft has no lock for Outlook either. What the two platforms give you instead comes down to three options.
- Switch signatures off. Microsoft lets an admin turn the signature feature off. Now nobody has a sunset photo, and nobody has a signature.
- Add a fixed footer on the server. Microsoft and Google can both attach text to outgoing mail after it is sent. Nobody can edit it. Nobody can see it while writing either, so people add their own on top. In a long email thread, Microsoft's footer ends up at the very bottom, under all the old replies. Google's is the same text for a whole department, with no names or titles.
- Write your own script. Some admins push the signatures out again on a schedule. It works until the script breaks, and then someone has to own it.
Each one solves part of the problem and leaves you with a new one. We compare the built-in routes in more detail for Google Workspace and for Microsoft 365 if you want the long version.
How BulkSignature solves it
We stopped looking for a lock and built the next best thing: the company signature is already there when someone starts writing, and it comes back by itself after someone changes it. No reminders involved.
Set it up once
You design the signature one time, in one dashboard. Names, job titles, phone numbers and photos come from the staff list you already keep in Google Workspace or Microsoft 365 (the directory), so nobody types their own details.
The directory is read again daily. When someone joins, they get the signature. When someone is promoted or gets a new phone number, the signature follows the directory. You change the title in one place, the place you were going to change it anyway.
In Gmail
BulkSignature puts the signature straight into each person's Gmail. There is nothing to install on their computer and nothing for them to copy and paste.
Then comes the part that ends the reminders. Daily Signature Sync puts the company version back once a day: in the evening if you are in the Americas, overnight in Europe. It is switched on by default. Whatever someone changed in their Gmail signature since the last sync is replaced with the approved one.
If you want more, add the BulkSignature for Gmail extension for Chrome. With it, people get the current company signature every time they start an email in Chrome, without waiting for the daily sync, and replies can carry their own shorter signature. You switch the extension on in BulkSignature, then roll it out to everyone from your Google admin account. Each person signs in the first time with a code we email them.
One place it does not reach: the Gmail app on a phone has its own separate signature, and if someone has typed one there, the phone uses that.
In Outlook
For Microsoft 365 there is one add-in. You roll it out once for everybody from your Microsoft 365 admin page, and employees do nothing. It usually shows up in Outlook within a day. Microsoft says it can take up to three.
From then on it adds the company signature to new emails, replies and forwards in Outlook on Windows, on Mac and on the web. On phones it covers new emails.
Microsoft 365 has no nightly sync, and it doesn't need one. The add-in fetches the current signature each time someone starts an email. Publish a change this afternoon, and it is in the next email people write.
What your week looks like
Monday, you publish the new signature.
Tuesday, the sales rep opens her Gmail settings and adds the sunset.
Wednesday morning, her Gmail signature is the company one again. Nobody sent a reminder. Nobody had a conversation about brand guidelines. She may try once more. The sync has more patience than she does.
Friday, you do something else with your afternoon.
What it does not do
This is still not a lock. People can change the text of a single email before they send it, and in Gmail an edit to the signature itself lasts until the next sync. What BulkSignature changes is the default: the right signature is the one that shows up, not a rule people have to remember.
If you have a legal line that must never be altered, keep the fixed server footer for that one line, and let the signature do the rest.
The options side by side
| Option | Can people change it? | Do they see it while writing? | Each person's own details? |
|---|---|---|---|
| Switch signatures off | There is nothing to change | No signature at all | No |
| Fixed footer added on the server | No | No | Basic ones in Microsoft 365, none in Google |
| Your own script | Yes, until the script runs again | Yes | Yes, if you build it |
| BulkSignature | Yes, but the company version comes back | Yes | Yes, from your directory |
FAQ
Can I lock an email signature in Outlook or Gmail?
No. Neither Microsoft 365 nor Google Workspace has a setting that stops people editing their signature. You can switch signatures off or add a fixed footer on the server, but neither gives you a personal, visible signature that stays put. The practical answer is to put the company signature back automatically.
What happens when an employee changes their signature?
In Gmail, their change stays until the next daily sync, then the company signature replaces it. In Outlook, the add-in adds the current company signature when they start their next email. In both, a person can still edit the text of the one email they are writing.
Does it work for both Outlook and Gmail?
Yes. For Google Workspace, BulkSignature sets the Gmail signature directly and refreshes it daily, with an optional Chrome extension. For Microsoft 365, an Outlook add-in adds the signature in Outlook on Windows, on Mac and on the web, and to new emails on phones.
Do employees need to install anything?
For Gmail, no: the signature goes into their Gmail without anything on their computer. The Chrome extension is optional, and an admin can roll it out for them. For Outlook, the admin rolls out one add-in for the whole company, so employees install nothing themselves.
Try it on your own team
Pick the five people most likely to add a sunset photo and start with them. BulkSignature has a 14-day free trial with no credit card required. Start the free trial.
