Hi, when I a log message with a double linebreak "A\n\nA" to SMTPAppender, the resulting Email is not formatted properly. The MIME parts are not parsed but are display as the message body. It looks like the double linebreak is written directly into the Subject-Header. With a single linebreak I get the same problem in Gmail. In Outlook the email is formatted properly, only the subject is cut at the linebreak. Could this be a bug in Logback? Regards, Arend Logging call: LoggerFactory.getLogger(Main.class).error("A\n\nA"); logback.xml: <configuration> <root> <appender class="ch.qos.logback.classic.net.SMTPAppender"> <smtpHost>... smtpHost</smtpHost> <to>... email</to> <subject>%logger{10} - %message</subject> <layout class="ch.qos.logback.classic.PatternLayout"> <pattern>%logger{10} - %message</pattern> </layout> </appender> </root> </configuration> Email subject: c.e.l.Main - A Visible email body: A MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_0_14393847.1372070958822" ------=_Part_0_14393847.1372070958822 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit c.e.l.Main - A A ------=_Part_0_14393847.1372070958822-- Email source: ... email headers To: ... Message-ID: ... Subject: c.e.l.Main - A A MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_0_14393847.1372070958822" ------=_Part_0_14393847.1372070958822 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit c.e.l.Main - A A ------=_Part_0_14393847.1372070958822--