Attachments

Attachments allow you to include supporting files with your email campaign message. These files are sent to every recipient and are limited to a combined total size of 20 MB per template.

Where to Manage Attachments

Attachments are managed in the Attachments tab of the email template editor during campaign creation or editing.

Adding Attachments

1. Open the Attachments tab in the template editor.
2. Click the upload area or drag and drop files to begin uploading. Files with potentially unsafe extensions are rejected (see Blocked File Types).
3. Each file uploads asynchronously; you can continue working on other parts of the template while uploads are in progress.

Size Limits

Limit	Value
Maximum total attachment size	20 MB per template
Number of attachments	No fixed limit (constrained by total size)

If the total size of all attachments exceeds 20 MB, further uploads are blocked. You must remove one or more attachments to free up space before adding new ones.

Blocked File Types

For security reasons, the following file extensions are blocked when uploading attachments to an Outreach email template. Attempting to upload a file with one of these extensions will result in the upload being rejected.

File name extension	File type
.ade	Access Project Extension (Microsoft)
.adp	Access Project (Microsoft)
.app	Executable Application
.application	ClickOnce Deployment Manifest File
.appref-ms	ClickOnce Application Reference File
.asp	Active Server Page
.aspx	Active Server Page Extended
.asx	ASF Redirector File
.bas	BASIC Source Code
.bat	Batch Processing
.bgi	Borland Graphics Interface
.cab	Windows Cabinet File
.cer	Internet Security Certificate File
.chm	Compiled HTML Help
.cmd	DOS CP/M Command File, Command File for Windows NT
.cnt	Microsoft Help Workshop Application
.com	Command
.cpl	Windows Control Panel Extension (Microsoft)
.crt	Certificate File
.csh	csh Script
.der	DER Encoded X509 Certificate File
.diagcab	Microsoft Diagnostics Cabinet File
.exe	Executable File
.fxp	FoxPro Compiled Source (Microsoft)
.gadget	Windows Vista Gadget
.grp	Microsoft Program Group
.hlp	Windows Help File
.hpj	AppWizard Help project
.hta	Hypertext Application
.htc	HTML Component File
.inf	Information or Setup File
.ins	IIS Internet Communications Settings (Microsoft)
.iso	Optical Disk Media File System
.isp	IIS Internet Service Provider Settings (Microsoft)
.its	Internet Document Set, Internet Translation
.jar	Java Archive
.jnlp	Java Network Launching Protocol
.js	JavaScript Source Code
.jse	JScript Encoded Script File
.ksh	UNIX Shell Script
.lnk	Windows Shortcut File
.mad	Access Module Shortcut (Microsoft)
.maf	Access (Microsoft)
.mag	Access Diagram Shortcut (Microsoft)
.mam	Access Macro Shortcut (Microsoft)
.maq	Access Query Shortcut (Microsoft)
.mar	Access Report Shortcut (Microsoft)
.mas	Access Stored Procedures (Microsoft)
.mat	Access Table Shortcut (Microsoft)
.mau	Media Attachment Unit
.mav	Access View Shortcut (Microsoft)
.maw	Access Data Access Page (Microsoft)
.mcf	Media Container Format
.mda	Access Add-in (Microsoft), MDA Access 2 Workgroup (Microsoft)
.mdb	Access Application (Microsoft), MDB Access Database (Microsoft)
.mde	Access MDE Database File (Microsoft)
.mdt	Access Add-in Data (Microsoft)
.mdw	Access Workgroup Information (Microsoft)
.mdz	Access Wizard Template (Microsoft)
.msc	Microsoft Management Console Snap-in Control File (Microsoft)
.msh	Microsoft Shell
.msh1	Microsoft Shell
.msh2	Microsoft Shell
.mshxml	Microsoft Shell
.msh1xml	Microsoft Shell
.msh2xml	Microsoft Shell
.msi	Windows Installer File (Microsoft)
.msp	Windows Installer Update
.mst	Windows SDK Setup Transform Script
.msu	Windows Update File
.ops	Office Profile Settings File
.osd	Open Software Description
.pcd	Visual Test (Microsoft)
.pif	Windows Program Information File (Microsoft)
.pl	Perl script
.plg	Developer Studio Build Log
.prf	Windows System File
.prg	Program File
.printerexport	Printer backup File
.ps1	Windows PowerShell
.ps1xml	Windows PowerShell
.ps2	Windows PowerShell
.ps2xml	Windows PowerShell
.psc1	Windows PowerShell
.psc2	Windows PowerShell
.psd1	Windows PowerShell
.psdm1	Windows PowerShell
.pst	MS Exchange Address Book File, Outlook Personal Folder File (Microsoft)
.py	Python Script
.pyc	Python Script
.pyo	Python Script
.pyw	Python Script
.pyz	Python Script
.pyzw	Python Script
.reg	Registration Information/Key for W95/98, Registry Data File
.scf	Windows Explorer Command
.scr	Windows Screen Saver
.sct	Windows Script Component, Foxpro Screen (Microsoft)
.shb	Windows Shortcut into a Document
.shs	Shell Scrap Object File
.theme	Desktop Theme File Settings
.tmp	Temporary File/Folder
.url	Internet Location
.vb	VBScript File or Any Visual Basic Source
.vbe	VBScript Encoded Script File
.vbp	Visual Basic Project File
.vbs	VBScript Script File, Visual Basic for Applications Script
.vhd	Virtual Hard Disk
.vhdx	Virtual Hard Disk Extended
.vsmacros	Visual Studio .NET Binary-based Macro Project (Microsoft)
.vsw	Visio Workspace File (Microsoft)
.webpnp	Internet Printing File
.website	Pinned Site Shortcut from Internet Explorer
.ws	Windows Script File
.wsc	Windows Script Component
.wsf	Windows Script File
.wsh	Windows Script Host Settings File
.xbap	Browser Applications
.xll	Excel Addin
.xnk	Exchange Public Folder Shortcut

Attachment States

Each attachment can be in one of the following states:

State	Description
Uploading	The file is being uploaded to storage. A progress indicator is shown.
Complete	The file has been successfully uploaded and is ready to send.
Failed	The upload encountered an error. The file can be retried.
Previously Uploaded	The file was uploaded in a prior session (e.g. when editing a campaign or importing a template).

Removing Attachments

• Click the remove button next to any attachment to delete it from the template.
• You can remove an attachment in any state, including while it is still uploading.
• Removing an uploading attachment immediately cancels the upload process.

Retrying Failed Uploads

If an attachment upload fails:

1. The attachment shows a Failed state with a retry option.
2. Click Retry to attempt the upload again.
3. Failed attachments are not automatically removed; they remain in the list until you retry or remove them.

Template Export and Import

When exporting or importing templates, attachments follow specific rules:

• Completed attachments are included in the export.
• Attachments that are still uploading or failed are excluded from the export.
• If any attachment is uploading when you trigger an export, you are warned that in-progress uploads will not be included.
• On import, attachments from the file are restored and marked to indicate they were imported from a previous export.

For the full guide to template import and export, including file types and editor matching rules, see Importing and Exporting Templates.

Run and Summary Modals

• When viewing a campaign summary or the Run Campaign modal, all attached files are listed.
• Each attachment can be downloaded individually from the summary or run modal.
• If the campaign has no attachments, the attachments section is hidden.

Best Practices

• Keep total attachment size well under 20 MB: large attachments increase delivery time and may be blocked by recipient email servers.
• Wait for uploads to complete before finishing or exporting the campaign.
• Retry failed uploads promptly: failed attachments are not sent with the campaign.
• Use common file formats (PDF, DOCX, XLSX, PNG, JPG) for maximum recipient compatibility.

Related Guidance

• Email Templates Overview. Overview of the email template system
• Choosing an Email Editor. Compare the Design and Code editors
• Creating a Campaign. Full campaign creation walkthrough