# Newsletters (/docs/supported-content/newsletters)



Newsletters enter eReader Relay only after they are delivered to a private subscription inbox.

## Supported email content [#supported-email-content]

* Standard MIME email with a readable HTML or text body.
* Common headings, paragraphs, lists, links, and supported inline images.
* Messages from a sender that has already been observed by your subscription inbox.

## Body and attachment handling [#body-and-attachment-handling]

| Email part                                                               | EPUB behavior                                            |
| ------------------------------------------------------------------------ | -------------------------------------------------------- |
| HTML body                                                                | Sanitized and used as the chapter                        |
| Plain-text body                                                          | Used as a readable fallback when HTML is unavailable     |
| Inline raster image referenced by the HTML                               | Included when its format and size pass the safety limits |
| Ordinary image attachment                                                | Ignored                                                  |
| PDF, Word document, spreadsheet, archive, calendar file, audio, or video | Ignored                                                  |

eReader Relay does not extract text from attachments, turn attachments into extra chapters, or place
downloadable attachments inside the EPUB. If the essential article exists only in an attached file,
the resulting chapter contains only the readable email body.

The complete inbound message must be no larger than 5 MB. Attachments contribute to that limit even
when they are ignored for EPUB generation.

For operational diagnosis, the original raw email is retained in private object storage. The raw
email can still contain attachment data even though attachments are not parsed or exposed in the
EPUB. A formal public retention period has not yet been published.

## Sanitization [#sanitization]

Email HTML is sanitized before it becomes a chapter. Scripts, forms, unsafe markup, trackers, and
other active content do not run in the EPUB. Newsletter advertising and decorative layout may be
removed or simplified as a result.

## Scheduling behavior [#scheduling-behavior]

Receiving a message does not immediately send a book. Add the observed newsletter to a reading list;
the message is then considered during **Run now** or the next scheduled edition. The first edition
uses the latest observed message, and later editions use messages newer than that list's saved
position.

## Not supported [#not-supported]

* Mail that never reaches the exact private subscription address.
* Content that exists only behind an authenticated link rather than in the email body.
* Content supplied only as an attachment.
* Interactive email features.
* Treating the subscription inbox as a general-purpose mailbox.

For delivery-to-inbox issues, see [Newsletter troubleshooting](/docs/troubleshooting/newsletters).