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original_url: "https://jace.pro/blog/setting-up-email-forwarding-to-basecamp-in-microsoft-365/"
format: markdown
ai_optimized: true
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Setting up Email Forwarding to Basecamp in Microsoft 365- # Setting up Email Forwarding to Basecamp in Microsoft 365

January 16, 2026 [microsoft365 ](/tags/microsoft365/)[email](/tags/email/)

  Enable AI Animation# [How to Set Up Email Forwarding to Basecamp in Microsoft 365](#how-to-set-up-email-forwarding-to-basecamp-in-microsoft-365)

This guide walks through setting up external email forwarding from a Microsoft 365 shared mailbox to Basecamp (or any external address)!

## [Overview](#overview)

Microsoft 365 has **two layers** that control email forwarding:

**Mailbox Forwarding Settings** - Where you configure *where* to forward emails
- **Outbound Spam Filter Policy** - Controls *whether* external forwarding is allowed

Both must be configured correctly, or forwarding will fail with error:

`550 5.7.520 Access denied, Your organization does not allow external forwarding. AS(7555)`
---
## [Step 1: Configure Mailbox Forwarding](#step-1-configure-mailbox-forwarding)

### [Via Exchange Admin Center](#via-exchange-admin-center)

- Go to [https://admin.exchange.microsoft.com](https://admin.exchange.microsoft.com)
- Navigate to **Recipients** → **Mailboxes**
- Select the shared mailbox (e.g., `team@example.com`)
- Click **Mail flow** → **Email forwarding**
- Enable **Forward all emails sent to this mailbox**
- Enter the Basecamp forwarding address (e.g., `save-not-real-value@3.basecamp.com`)
- Optionally check **Keep a copy of forwarded messages**
- Save

### [Via PowerShell](#via-powershell)

```
`# Connect to Exchange Online
Connect-ExchangeOnline -UserPrincipalName your-admin@domain.com -Device

# Set forwarding address
Set-Mailbox -Identity "team@example.com" `
    -ForwardingSmtpAddress "smtp:save-not-real-value@3.basecamp.com" `
    -DeliverToMailboxAndForward $true

# Verify
Get-Mailbox -Identity "team@example.com" | Format-List ForwardingSmtpAddress,DeliverToMailboxAndForward`
```

---
## [Step 2: Allow External Forwarding in Anti-Spam Policy](#step-2-allow-external-forwarding-in-anti-spam-policy)

This is the step that’s often missed. By default, Microsoft 365 blocks external forwarding.

### [Option A: Add to Existing Policy (If You Already Have One)](#option-a-add-to-existing-policy-if-you-already-have-one)

If you already have an outbound spam filter rule allowing forwarding for other mailboxes:

#### [Via PowerShell](#via-powershell-1)

`# Connect to Exchange Online
Connect-ExchangeOnline -UserPrincipalName your-admin@domain.com -Device

# Check existing rules
Get-HostedOutboundSpamFilterRule | Format-List Name,From,State

# Add the new mailbox to an existing rule
Set-HostedOutboundSpamFilterRule -Identity "Your Rule Name" `
    -From "existing@domain.com","team@example.com"

# Verify
Get-HostedOutboundSpamFilterRule -Identity "Your Rule Name" | Format-List Name,From`### [Option B: Create New Policy and Rule](#option-b-create-new-policy-and-rule)

If you don’t have an existing forwarding policy:

#### [Via Microsoft 365 Defender Portal](#via-microsoft-365-defender-portal)

- Go to [https://security.microsoft.com](https://security.microsoft.com)
- Navigate to **Email & collaboration** → **Policies & rules** → **Threat policies**
- Click **Anti-spam**
- Go to **Outbound policies** tab
- Click **Create policy** → **Outbound**
- Configure:
**Name**: “Allow External Forwarding”
- **Automatic forwarding**: Set to **On - Forwarding is enabled**

- Under **Applied to**, add the mailboxes that need forwarding:
**From**: `team@example.com`

- Save

#### [Via PowerShell](#via-powershell-2)

`# Connect to Exchange Online
Connect-ExchangeOnline -UserPrincipalName your-admin@domain.com -Device

# Create new outbound spam filter policy with forwarding enabled
New-HostedOutboundSpamFilterPolicy -Name "AllowForwarding" -AutoForwardingMode On

# Create rule to apply policy to specific mailboxes
New-HostedOutboundSpamFilterRule -Name "Allow External Forwarding" `
    -HostedOutboundSpamFilterPolicy "AllowForwarding" `
    -From "team@example.com"

# Verify
Get-HostedOutboundSpamFilterRule | Format-List Name,From,HostedOutboundSpamFilterPolicy,State`
---
## [Troubleshooting](#troubleshooting)

### [Check Current Forwarding Settings](#check-current-forwarding-settings)

```
`Get-Mailbox -Identity "team@example.com" | Format-List Name,ForwardingAddress,ForwardingSmtpAddress,DeliverToMailboxAndForward`
```

### [Check Outbound Spam Filter Policies](#check-outbound-spam-filter-policies)

```
`# List all policies
Get-HostedOutboundSpamFilterPolicy | Format-List Name,AutoForwardingMode

# List all rules (shows which users/mailboxes each policy applies to)
Get-HostedOutboundSpamFilterRule | Format-List Name,HostedOutboundSpamFilterPolicy,From,State`
```

### [Check Remote Domain Settings](#check-remote-domain-settings)

```
`Get-RemoteDomain | Format-List DomainName,AutoForwardEnabled`
```

---
## [Quick Reference](#quick-reference)

SettingLocationPurposeForwardingSmtpAddressExchange Admin → MailboxWhere to forward emailsAutoForwardingModeDefender → Anti-spam → OutboundWhether forwarding is allowedHostedOutboundSpamFilterRuleDefender → Anti-spam → OutboundWhich mailboxes the policy applies to
---
## [Common Errors](#common-errors)

ErrorCauseFix`550 5.7.520 Access denied... AS(7555)`Outbound spam policy blocking forwardingAdd mailbox to spam filter rule with `AutoForwardingMode = On`Forwarding not working (no error)ForwardingSmtpAddress not setConfigure mailbox forwarding in Exchange Admin
---
## [Notes](#notes)

- Changes typically take effect within a few minutes
- The “Default” outbound spam policy has `AutoForwardingMode = Automatic` which blocks external forwarding
- You must create a custom policy with `AutoForwardingMode = On` and apply it to mailboxes that need forwarding

---
[View this page on GitHub](https://github.com/jacebenson/jace.pro/tree/main/./src/posts/2026/2026-01-18-setup-office365-forwarding-from-exchange.md).

[Setting up Email Forwarding to Basecamp in Microsoft 365](https://jace.pro/blog/setting-up-email-forwarding-to-basecamp-in-microsoft-365/) [Jace Benson](https://jace.pro) ![Jace Benson](https://jace.pro/icon-512x512.png)

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*This content is from Jace Benson's ServiceNow and tech blog at jace.pro*
*Original post: https://jace.pro/blog/setting-up-email-forwarding-to-basecamp-in-microsoft-365/*