From 09f047ab8bebb10514ed0135bcb26cb19fa484f7 Mon Sep 17 00:00:00 2001
From: Fabrizio Steiner <stffabi@users.noreply.github.com>
Date: Tue, 23 Jan 2018 20:05:18 +0100
Subject: [PATCH] Send mails that correspond to RFC2045 with a base64 line
 limit of 76 characters.

---
 notifications/email.go |  7 ++++++-
 notifications/util.go  | 24 ++++++++++++++++++++++++
 2 files changed, 30 insertions(+), 1 deletion(-)
 create mode 100644 notifications/util.go

diff --git a/notifications/email.go b/notifications/email.go
index 6850ca9..5380f7f 100644
--- a/notifications/email.go
+++ b/notifications/email.go
@@ -72,7 +72,12 @@ func (e *emailTypeNotifier) buildMessage(entries []*log.Entry) []byte {
 	for k, v := range header {
 		message += fmt.Sprintf("%s: %s\r\n", k, v)
 	}
-	message += "\r\n" + base64.StdEncoding.EncodeToString([]byte(body))
+
+	encodedBody := base64.StdEncoding.EncodeToString([]byte(body))
+	//RFC 2045 base64 encoding demands line no longer than 76 characters.
+	for _, line := range SplitSubN(encodedBody, 76) {
+		message += "\r\n" + line
+	}
 
 	return []byte(message)
 }
diff --git a/notifications/util.go b/notifications/util.go
new file mode 100644
index 0000000..5764341
--- /dev/null
+++ b/notifications/util.go
@@ -0,0 +1,24 @@
+package notifications
+
+import "bytes"
+
+// SplitSubN splits a string into a list of string with each having
+// a maximum number of characters n
+func SplitSubN(s string, n int) []string {
+	sub := ""
+	subs := []string{}
+
+	runes := bytes.Runes([]byte(s))
+	l := len(runes)
+	for i, r := range runes {
+		sub = sub + string(r)
+		if (i+1)%n == 0 {
+			subs = append(subs, sub)
+			sub = ""
+		} else if (i + 1) == l {
+			subs = append(subs, sub)
+		}
+	}
+
+	return subs
+}