The HubSpot integration automatically adds your Letsignit email signatures and campaigns to one-to-one emails and sales sequences sent from HubSpot, while keeping everything centrally managed in your Letsignit platform.
Integration compatibility
The integration only works with Microsoft 365 (Exchange Online) mailboxes connected to HubSpot.
It does not support:
Other email services, including Google Workspace, on-premises Exchange servers, and IMAP/SMTP connections.
HubSpot marketing emails or emails sent directly from HubSpot's own servers.
Before you start
Make sure you have the following access:
A Letsignit Global Administrator account.
Administrator access to Microsoft Exchange Online.
Administrator access to HubSpot.
The users concerned must also have a Microsoft 365 mailbox that can be connected to HubSpot.
The 3 configuration steps
Enter your domain names used to send emails.
Configure Microsoft Exchange to route HubSpot emails through Letsignit.
Configure HubSpot to allow users to connect their mailboxes and use Letsignit signatures.
Access the HubSpot integration
Sign in to your Letsignit platform.
Go to Configuration > Integrations > Signature deployment > CRM.
Find the HubSpot integration and click Connect.
Follow the three steps below to complete the setup.
1. Enter your domain names
From the HubSpot integration in your Letsignit platform, start by entering the domain names used to send emails from HubSpot.
Enter your organization's domain name(s), for example company.com.
For each domain, Letsignit displays the associated Microsoft 365 mail server, usually in the form company-com.mail.protection.outlook.com.
Check that the server shown matches the one used by your organization.
Confirm the information to continue to the next step.
Important: This verification is essential to ensure your emails are routed correctly. An incorrect mail server configuration may cause delivery issues or even email loss.
2. Configure Exchange Online for HubSpot emails
This step configures Microsoft Exchange Online so that emails sent from HubSpot automatically pass through Letsignit, where your signature is added before the email reaches its recipient.
Emails sent from Outlook are not affected by this setup and continue to use the Letsignit Outlook add-in.
Before you start
You need the Exchange Administrator (or Global Administrator) role in Microsoft 365.
The following IP addresses and server name apply to Letsignit accounts hosted in Europe. If your account is hosted in another region, contact Letsignit support for the appropriate values.
Setting | Value |
Letsignit IP addresses | 40.66.63.89, 40.66.63.90, 40.66.63.91 |
Letsignit server | lsicloud-smtp.letsignit.com |
Already using Letsignit server-side signatures for all your emails?
If an Exchange rule already routes all your outgoing emails to Letsignit, no additional configuration is required for HubSpot.
If this rule only applies to certain users or domains, make sure it also covers those used in HubSpot.
Important: make sure the rule applies only to outgoing emails (The sender > is external/internal > Inside the organization) and not to All messages, to avoid routing incoming emails through Letsignit.
You can then go directly to section 3: Configure HubSpot.
Step 1 - Create the connector that receives emails from Letsignit
In the Exchange admin center, go to Mail flow > Connectors and click
Add a connector.Under Connection from, select Your organization's email server, then click Next.
Give the connector a name, for example From Letsignit. Keep Turn it on and
Retain internal Exchange email headers ticked, then click Next.Select By verifying that the IP address of the sending server matches one of the following IP addresses, add the three Letsignit IP addresses one by one, then click Next.
Review the settings and click Create connector.
Step 2 - Create the connector that sends emails to Letsignit
In Mail flow > Connectors, click Add a connector.
Under Connection from, select Office 365. Under Connection to, select
Your organization's email server. Click Next.Give the connector a name that shows where emails go, for example
To lsicloud-smtp.letsignit.com. Keep Turn it on ticked, then click Next.Under Use of connector, select Only when I have a transport rule set up that redirects messages to this connector, then click Next.
Under Routing, add the smart host lsicloud-smtp.letsignit.com, then click Next.
Under Security restrictions, tick Always use Transport Layer Security (TLS), select Issued by a trusted certificate authority (CA), tick And the subject name or subject alternative name (SAN) matches this domain name, enter lsicloud-smtp.letsignit.com, then click Next.
Enter an external email address to validate the connector and click Validate. The
validation succeeds only if step 1 is done. Then click Create connector.
Step 3 - Prepare Exchange Online
These two settings are part of every Letsignit server-side setup. Skip them if they are already in place.
Message format: go to Mail flow > Remote domains, open the Default remote domain and click Edit text and character set. Set Use rich-text format to Never, then save. Letsignit can then read the emails it receives (no winmail.dat attachments).
Connection filter: in the Microsoft Defender portal, go to Email & collaboration >
Policies & rules > Threat policies > Anti-spam. Open Connection filter policy
(Default), click Edit connection filter, add the three Letsignit IP addresses to
Always allow messages from the following IP addresses or address range, then save. Emails coming back from Letsignit are then not treated as spam.
Step 4 - Create the transport rule for HubSpot emails
In the Exchange admin center, go to Mail flow > Rules, click Add a rule, then
Create a new rule.Give the rule a name, for example Letsignit - HubSpot.
Under Apply this rule if, select The message headers > matches these text patterns. Enter the header name x-hs-fax-cid and the pattern (\S). HubSpot adds this header to every email sent through a connected mailbox: this condition is what limits the rule to HubSpot emails.
Click + to add a condition: The sender > is external/internal >
Inside the organization.Click + to add a condition: The sender > address matches any of these text patterns.
Enter one pattern per email domain managed in Letsignit, for example @contoso.com$.Do not skip the domain filter. HubSpot emails that your users receive from other companies carry the same header. The sender conditions keep them out of the rule, and they also leave out domains of your organization that are not managed in Letsignit.
Under Do the following, select Redirect the message to > the following connector,
then select the connector created in step 2.
Under Except if, add these four exceptions:
Exception | Value | Why |
The message headers > include any of these words | Header: | The email has already been signed by Letsignit. This exception prevents a loop: never remove it. |
The sender > address matches any of these text patterns |
| Emails with an empty sender, such as delivery reports. |
The message properties > include the message type | Calendaring | Meeting invitations and replies. |
The message > size is greater than or equal to |
| Emails above the size accepted by Letsignit. |
Click Next. In the rule settings, keep the mode Enforce, tick Stop processing more
rules, and set Match sender address in message to Envelope. Click Next, review
the rule and click Finish.
New rules are created disabled. Select the rule in the list and turn on
Enable or disable rule.
Enable it for selected users only
You do not have to turn on Letsignit signatures for HubSpot emails for everybody at once, for
example to start with a pilot group or with your sales team only. In step 4, add one more condition:The sender > is this person, then select the users, or
The sender > is a member of this group, then select a group. Use a group if you want to add users later without editing the rule.
Keep the header and domain conditions. HubSpot emails from other users are sent as before, without the Letsignit signature.
Step 5 - Check that it works
Ask a user to follow the user guide: connect their Microsoft 365 mailbox to
HubSpot and remove their HubSpot signature.From HubSpot, the user sends an email to an external address you can read. The email received shows the Letsignit signature, and its headers contain X-LSI-Version.
In the Exchange admin center, open Mail flow > Message trace and search for thisemail: it went through your rule and the connector to Letsignit. An email sent from Outlook by the same user does not go through this rule.
If a Letsignit rule for all emails is also enabled, it signs HubSpot emails too, and this test does not show that the HubSpot rule works. Run the test while that rule is disabled.
Good to know
HubSpot header: x-hs-fax-cid is a technical header set by HubSpot, not a documented setting. If HubSpot renames or removes it, HubSpot emails are still delivered but no longer get the Letsignit signature, without any error. Send a test email from HubSpot from time to time.
Sent copy: the copy in the user's Sent Items folder and in the HubSpot timeline does not show the signature. Letsignit adds the signature after the email leaves the mailbox.
Not covered: Gmail and Google Workspace mailboxes connected to HubSpotHubSpot marketing emails, and emails sent by HubSpot without a connected mailbox: they are sent by HubSpot's own servers and never reach your Exchange Online organizationmailboxes connected to HubSpot through IMAP/SMTP ("other provider")
Data: HubSpot emails are processed by Letsignit in transit only, like any email sent through Letsignit server-side signatures. Nothing new is stored.
Troubleshooting
Problem | What to check |
HubSpot emails not signed | The rule is enabled. The header name is x-hs-fax-cid. The sender address matches one of the domain patterns. In HubSpot, the user's mailbox shows Inbox type: Outlook 365. Message trace shows whether the rule applied. |
Outlook emails also go to Letsignit | The x-hs-fax-cid header condition is missing from the rule. |
Email signed twice, or delivery loop | The X-LSI-Version exception is missing from the rule. |
Two signatures (HubSpot and Letsignit) | The user's HubSpot signature is still set (see the user guide, step 2). |
A user cannot see Connect email account in HubSpot | Personal email access is off for this user (see the HubSpot administrator guide). |
Connector validation fails | The connector receiving emails from Letsignit (step 1) is missing, or its IP addresses are wrong. |
3. Configure email sending in HubSpot
This step covers granting permissions as a HubSpot administrator and connecting each user’s Microsoft 365 mailbox.
3.1. For the HubSpot administrator
Step 1 - Give your users personal email access
Users who can already see Connect email account in their HubSpot email settings have this
access: skip them.
In HubSpot, open Settings (gear icon) and go to Account Management > Users & Teams.
Select the users who will send emails from HubSpot, then click Edit permissions.
You can edit several users at once only if they have the same seat type.In the left menu, under Account, click Account settings. In Settings access, turn on Personal email access, then click Save at the top right.
Step 2 - Share this FAQ with users
Share this FAQ with the relevant users so they can follow the instructions to connect their Microsoft 365 mailbox to HubSpot and remove their HubSpot signature, preventing recipients from receiving two signatures.
Good to know
Mailbox type: only Microsoft 365 mailboxes, connected to HubSpot as Outlook 365, get the
Letsignit signature. Gmail and Google Workspace mailboxes, and mailboxes connected through
IMAP/SMTP ("other provider"), are not covered.Marketing emails: HubSpot marketing emails, and emails sent by HubSpot without a connected
mailbox, are sent by HubSpot's own servers. They do not get the Letsignit signature.Unsubscribe line: HubSpot may add an unsubscribe line to one-to-one emails (for example "Prefer fewer emails from me? Click here"). It comes from the Include unsubscribe link option, not from the signature, and Letsignit does not remove it.
Troubleshooting
Problem | What to check |
A user cannot see Connect email account | Personal email access is off for this user (step 1). |
A user's HubSpot emails have no Letsignit signature | In the user's email settings, the mailbox shows Inbox type: Outlook 365. Your Microsoft 365 administrator has finished the Exchange Online setup. |
Recipients receive two signatures | The user's HubSpot signature is still set (see the user guide, step 2). |
3.2. For each HubSpot user
Step 1 - Connect your Microsoft 365 mailbox to HubSpot
In HubSpot, click Settings (gear icon). In the left menu, under Your Preferences, click
General, select the Email tab, then click Connect email account.Turn on inbox automation is optional and has no effect on your Letsignit signature: tick it
only if your company uses this HubSpot feature. Then click Connect your inbox.Enter your work email address and click Next.
HubSpot detects that your mailbox is hosted by Microsoft. Click Connect to Outlook 365.
Check that the address shown is yours (otherwise click Connect a different account),
review what HubSpot will access, then click Continue.Sign in with your Microsoft 365 account and accept the requested permissions.
If Microsoft asks for administrator approval, contact your Microsoft 365 administrator.HubSpot confirms the connection and offers to download its extension. It is not needed for
your Letsignit signature: click No, thanks. In Outlook, keep using the Letsignit add-in as
usual.Back on the Email tab, your mailbox is listed with Inbox type: Outlook 365 and the status Enabled. You can close the Pro tip banners about HubSpot's add-in and Chrome extension: they are not needed for your Letsignit signature.
Step 2 - Remove your HubSpot signature
HubSpot cannot tell that Letsignit adds a signature. If you keep a signature in HubSpot, your recipients will receive two signatures.
Go back to Settings > General > Email tab (see step 1).
Under Configure, click Manage email signatures.
Delete all the content of the signature so that the editor is empty, then click Save.
HubSpot may also add an unsubscribe line to one-to-one emails (for example "Prefer fewer emails from me? Click here"). It comes from the Include unsubscribe link option under Configure, not from your signature, and Letsignit does not remove it. If you cannot change this option, your HubSpot administrator manages it.
Check that it works
Send an email from a HubSpot contact record to a colleague or to an external address you can read.
The email received should show your Letsignit signature.
Good to know
Sent copy: the copy in your Outlook Sent Items folder and in the HubSpot timeline does not
show the signature. This is expected: Letsignit adds the signature after the email leaves your
mailbox, so your recipients always receive it.Replies: in a reply, the signature is placed above the quoted message.
Not covered:
Gmail and Google Workspace mailboxes connected to HubSpot
HubSpot marketing emails, and emails sent by HubSpot without a connected mailbox: they are
sent by HubSpot's own servers, not by your Microsoft 365 mailboxmailboxes connected to HubSpot through IMAP/SMTP ("other provider")
Troubleshooting
Problem | What to check |
No Connect email account button | Your HubSpot administrator has not allowed you to connect a personal mailbox yet. |
No Letsignit signature | On the Email tab, your mailbox shows Inbox type: Outlook 365 (step 1), and your Microsoft 365 administrator has set up Letsignit for HubSpot emails. |
Two signatures | Your HubSpot signature is still set (step 2). |
Signature missing in Sent Items or the HubSpot timeline | Expected, see "Good to know". |