---
title: setMimeType
slug: campaign/docs/setmimetype
createdAt: 2026-07-02T19:01:46.737Z
---

**Type**: void

**Parameters**

| Name      | Type   | Value                                                                   |
| --------- | ------ | ----------------------------------------------------------------------- |
| sessionId | String | ID of the session                                                       |
| mailingId | long   | ID of the mailing                                                       |
| mimeType  | String | MIME type of the mailing (text/plain, text/html, multipart/alternative) |

**Return values**

- **Code structure**

```javascript
void setMimeType(String sessionId, long mailingId, String mimeType)
```