Attachments
Attachments are supporting files sent with an email. Every recipient receives the same files, up to a combined total of 20 MB per template.
Where to Manage Attachments
Attachments are managed on the Attachments tab of the email template editor, whether the template is being created in the library or built inside a campaign.
Adding Attachments
- Open the Attachments tab in the template editor.
- Click the upload area or drag and drop files to begin uploading. Files with potentially unsafe extensions are rejected (see Blocked File Types).
- Each file uploads on its own, so the rest of the template can be worked on while uploads finish.
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
- Select the remove button next to any attachment to take it off the template.
- An attachment can be removed in any state, including while it is still uploading.
- Removing an uploading attachment immediately cancels the upload.
Deleting a Template That Has Attachments
Deleting a template that carries attachments shows an extra warning in the delete confirmation, because the files go with it.
Campaigns that already use the template keep sending, but without the files. The message content still goes out as before and nothing else about the campaign changes. To keep the files in play, upload them to a replacement template before deleting the original. See Managing Templates.
Retrying Failed Uploads
If an attachment upload fails:
- The attachment shows a Failed state with a retry option.
- Select Retry to attempt the upload again.
- Failed attachments are not removed automatically. They stay in the list until retried or removed.
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 an export is triggered, a warning explains 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.
Attachments in a Campaign
- A campaign summary and the run confirmation both list every attached file.
- Each attachment can be downloaded individually from either place.
- Where there are no attachments, the section is hidden.
Best Practices
- Keep the total well under 20 MB. Large attachments slow delivery and may be blocked by recipient email servers.
- Wait for uploads to complete before saving or exporting the template.
- Retry failed uploads promptly. A failed attachment is not sent.
- Use common file formats (PDF, DOCX, XLSX, PNG, JPG) for the widest recipient compatibility.
Related Guidance
- Email Templates Overview. How the email template overlay fits together
- Managing Templates. Edit, duplicate and delete a saved template
- Adding a Template. Applying a template to a campaign