Bulk Import

The bulk import tool lets you schedule many posts at once by uploading a CSV file. Open it from the + create menu → Bulk Import; it submits to POST /posts/bulk. Each row is created independently, and the batch returns per-row results so individual failures don't block the rest.

Data format

Bulk import accepts a CSV file (up to 5 MB) whose first line is a header row. Headers are matched case-insensitively by name, so column order doesn't matter. Quoted fields may contain commas and line breaks.

Supported columns

Column	Required	Description
content	Yes	The post body text.
schedule_at (or date)	Yes	Scheduled publish date and time as an ISO 8601 date string.
channel	Yes	One or more channels, separated by semicolons (e.g. x;linkedin). Each value is a channel ID or a provider identifier; a provider identifier matches your first connected channel of that provider. Up to 50 channels per row.
media_url	No	A public https:// URL of one image or video. It is downloaded into your media library and attached to every channel post for that row. See Media for limits.
campaign_id	No	ID of an existing campaign to assign the post to.

A single request accepts up to 100 rows.

Preview

After you pick a file, the tool shows a Preview table (content, channels, schedule) of the parsed rows. A missing required header, an empty file, or a file with no data rows is reported before anything is sent. Click Import All to submit.

Media

When a row has a media_url, Postmill downloads the file once, saves it to your organisation's media library (it appears there like any other upload), and attaches it to each of the row's posts.

• The URL must be https:// and point to a public host — http://, private/internal addresses, and URLs that redirect to them are rejected.
• Supported types: images (JPEG, PNG, GIF, WebP, AVIF, BMP, TIFF) and video (MP4, WebM, QuickTime). Audio and other file types are rejected.
• Maximum size is 512 MB, and the file counts toward your organisation's storage quota.
• If the download fails for any reason (bad URL, the source returns an error, unsupported type, too large, quota exceeded), the whole row fails with an error starting "Could not import media_url" — no posts are created for it, so you never end up with posts silently missing their media.

Campaign targeting

If you specify a campaign_id column, posts are assigned to that campaign during import. The campaign must already exist in your Postmill organisation. See Campaigns for creating and managing campaigns.

Validation

Each row is checked as it is imported:

• Date — a scheduled date in the past fails the row ("Cannot schedule a post in the past").
• Media — a media_url that cannot be imported fails the row (see Media).
• Channels — a channel that is not connected, or is disabled, is skipped with a warning; the row still succeeds for its other channels.
• Channel rules — each post is checked against the same per-channel rules the composer applies (required channel settings, each channel's media requirements, character limits). A post that breaks them is not created and is reported as a warning for that channel (e.g. Failed to create post for "x": post is too long, please fix it); the row still succeeds for its other channels. Because bulk import sends no channel-specific settings, channels that require them (for example a Pinterest board or a YouTube title) fail this check — schedule those from the composer.
• Post quota — when billing is enabled, the whole batch (rows × channels) is checked against your plan's monthly post limit before any row is created.

Rows that fail are reported but do not halt the import.

Results view

After processing, the bulk import shows a per-row Results table:

Result column	Meaning
Status	Success or Failed.
Details	Created, or the warnings (e.g. a skipped channel or a channel-rule failure) and the error that failed the row.

A row succeeds when at least one post was created for it. Failed rows are skipped entirely — fix the issues, re-upload just those rows, and re-run.

Batch integrity

The batch import does not use a database transaction across all rows. Each row is an independent creation. This means:

• A failed row never prevents successful rows from being created.
• There is no rollback — if you need to remove successfully created posts from a partially failed batch, use the calendar to delete them individually.

Usage tips

• Test with a small batch first — upload 3-5 rows to verify your columns and content format before importing hundreds.
• Use the campaign column for imports that are part of a campaign launch.
• Pre-flight channels — verify all target channels are connected and healthy before importing; unknown or disabled channels are skipped.
• Date formats — ISO 8601 (2026-06-09T14:30:00Z) is required. Include timezone offsets to avoid ambiguity.

Verified against v1.3.0