@lacspace/mime
Isomorphic RFC 5322 / RFC 2045-2049 MIME parser and builder for webmail. parseMime() turns raw mail (string or bytes) into from/to/cc/subject/date/text/html/attachments/inline cid images/priority/List-Unsubscribe one-click and the part tree; handles nested multipart (mixed, alternative, related, report, signed), message/rfc822 forwards, base64 and quoted-printable (tolerant), RFC 2047 encoded words (split multibyte, adjacent whitespace), RFC 2231 parameters, 30+ charsets and malformed input without ever throwing. parseBodyStructure() parses IMAP BODYSTRUCTURE (literals, extension data) into the same tree with IMAP partIds, plus findTextParts / listAttachments / decodePart for lazy fetching. buildMime() writes CRLF messages with encoded-word headers, QP/base64 bodies, mixed/alternative/related nesting, Message-ID generation and header-injection guards; replyHeaders() / forwardSubject() for threading. Pairs with @lacspace/imap and @lacspace/mailer. Zero dependencies; Node 18+, edge runtimes and browsers.
npm i @lacspace/mimeUsage
import { parseMime, buildMime, replyHeaders, parseBodyStructure, findTextParts, listAttachments, decodePart } from "@lacspace/mime";
const mail = parseMime(rawBytesOrString);
mail.from; // { name: "Rām Bahādur", address: "ram@gmail.com" }
mail.subject; // "नमस्ते दुनिया" (RFC 2047, split multibyte joined)
mail.html ?? mail.text;
mail.inline; // cid images from multipart/related → [{ contentId, content, … }]
mail.attachments; // [{ partId: "2", filename: "Q3 Report.pdf", size, content: Uint8Array }, …]
mail.listUnsubscribe; // { urls: ["https://…"], mailto: "mailto:…", oneClick: true }
// Lazy webmail: classify from BODYSTRUCTURE, then fetch by partId.
const tree = parseBodyStructure(fetchResult.bodyStructure); // object from @lacspace/imap, or the raw IMAP string
const { text, html } = findTextParts(tree); // e.g. html.partId === "1.2"
const body = decodePart(await fetchPart(html.partId), html); // transfer-decoded + charset → string
listAttachments(tree); // [{ partId: "2", filename, size, isInline }, …]
// Reply
const raw = buildMime({ from: "me@lacspace.com", to: mail.from!, text: "Thanks!", ...replyHeaders(mail) });Exports 33
MailHeadersMimeErrorbuildMimedecodeBase64decodeCharsetdecodePartdecodeQuotedPrintabledecodeWordsencodeBase64encodeHeaderencodeQuotedPrintableencodeWordfindTextPartsfoldTextformatAddressformatAddressListforwardSubjectgenerateMessageIdguessContentTypelistAttachmentsnormalizeCharsetparseAddressparseAddressListparseBodyStructureparseDateparseHeaderParamsparseHeadersparseMessageIdsparseMimereplyHeadersreplySubjectrfc2822Datewrap76Keywords
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