diff --git a/go.mod b/go.mod
index 507742b..1fee12c 100644
--- a/go.mod
+++ b/go.mod
@@ -7,6 +7,7 @@ require (
 	github.com/google/uuid v1.6.0
 	github.com/joho/godotenv v1.5.1
 	github.com/jung-kurt/gofpdf v1.16.2
+	golang.org/x/image v0.18.0
 	modernc.org/sqlite v1.37.1
 )
 
diff --git a/go.sum b/go.sum
index 9c2ba80..4464ff0 100644
--- a/go.sum
+++ b/go.sum
@@ -27,6 +27,8 @@ github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXf
 golang.org/x/exp v0.0.0-20250408133849-7e4ce0ab07d0 h1:R84qjqJb5nVJMxqWYb3np9L5ZsaDtB+a39EqjV0JSUM=
 golang.org/x/exp v0.0.0-20250408133849-7e4ce0ab07d0/go.mod h1:S9Xr4PYopiDyqSyp5NjCrhFrqg6A5zA2E/iPHPhqnS8=
 golang.org/x/image v0.0.0-20190910094157-69e4b8554b2a/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
+golang.org/x/image v0.18.0 h1:jGzIakQa/ZXI1I0Fxvaa9W7yP25TqT6cHIHn+6CqvSQ=
+golang.org/x/image v0.18.0/go.mod h1:4yyo5vMFQjVjUcVk4jEQcU9MGy/rulF5WvUILseCM2E=
 golang.org/x/mod v0.24.0 h1:ZfthKaKaT4NrhGVZHO1/WDTwGES4De8KtWO0SIbNJMU=
 golang.org/x/mod v0.24.0/go.mod h1:IXM97Txy2VM4PJ3gI61r1YEk/gAj6zAHN3AdZt6S9Ww=
 golang.org/x/sync v0.14.0 h1:woo0S4Yywslg6hp4eUFjTVOyKt0RookbpAHG4c1HmhQ=
diff --git a/internal/handlers/expenses.go b/internal/handlers/expenses.go
index 2b9ded8..cef7d36 100644
--- a/internal/handlers/expenses.go
+++ b/internal/handlers/expenses.go
@@ -5,9 +5,12 @@
 package handlers
 
 import (
+	"bytes"
 	"database/sql"
 	"fmt"
 	"html/template"
+	"image"
+	"image/jpeg"
 	"io"
 	"log"
 	"net/http"
@@ -19,6 +22,7 @@ import (
 	"time"
 
 	"github.com/go-chi/chi/v5"
+	"golang.org/x/image/draw"
 
 	"github.com/cclohmar/ReceiptNext/internal/ai"
 	"github.com/cclohmar/ReceiptNext/internal/database"
@@ -101,6 +105,17 @@ func (h *ExpenseHandler) UploadReceipt(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	// Resize the image (max 2048px, JPEG 85%) to keep attachment sizes manageable
+	// and prevent SMTP size-limit rejections when filing events with many receipts.
+	resized, resizeErr := resizeImage(fileData)
+	if resizeErr == nil && len(resized) > 0 {
+		fileData = resized
+		// If the original was not JPEG, update extension since output is always JPEG.
+		if ext != "jpg" && ext != "jpeg" {
+			ext = "jpg"
+		}
+	}
+
 	// 6. Generate a UUID-based filename and ensure the storage directory exists.
 	filename := utils.NewUUID() + "." + ext
 	storagePath := filepath.Join("storage", filename)
@@ -659,3 +674,46 @@ func detectImageExtension(data []byte) string {
 
 	return ""
 }
+
+// ---------------------------------------------------------------------------
+// Image processing helpers
+// ---------------------------------------------------------------------------
+
+// resizeImage resizes image data to a maximum of 2048 pixels on the longest
+// side while maintaining aspect ratio. Output is always JPEG at 85% quality.
+// Returns the original data unchanged if the image is already smaller, or if
+// decoding/resizing fails (e.g. unsupported format like HEIC).
+func resizeImage(data []byte) ([]byte, error) {
+	img, _, err := image.Decode(bytes.NewReader(data))
+	if err != nil {
+		return data, err
+	}
+
+	bounds := img.Bounds()
+	w, h := bounds.Dx(), bounds.Dy()
+
+	const maxDim = 2048
+	if w <= maxDim && h <= maxDim {
+		return data, nil // already small enough
+	}
+
+	// Maintain aspect ratio.
+	var newW, newH int
+	if w > h {
+		newW = maxDim
+		newH = h * maxDim / w
+	} else {
+		newH = maxDim
+		newW = w * maxDim / h
+	}
+
+	dst := image.NewRGBA(image.Rect(0, 0, newW, newH))
+	draw.CatmullRom.Scale(dst, dst.Bounds(), img, bounds, draw.Over, nil)
+
+	var buf bytes.Buffer
+	if err := jpeg.Encode(&buf, dst, &jpeg.Options{Quality: 85}); err != nil {
+		return data, err
+	}
+
+	return buf.Bytes(), nil
+}