Updated FAQ

FAQ.md

@@ -1612,6 +1612,7 @@ Too large messages and triggering the spam filter of an email server are the mos
 * *451 4.7.0 Temporary server error. Please try again later. PRX4 ...* indicates a server configuration problem, please [see here](https://www.limilabs.com/blog/office365-temporary-server-error-please-try-again-later-prx4) or [see here](https://judeperera.wordpress.com/2019/10/11/fixing-451-4-7-0-temporary-server-error-please-try-again-later-prx4/).
 * *451 4.7.0 Temporary server error. Please try again later. PRX5 ...* indicates a server configuration problem, please [see here](https://www.limilabs.com/qa/4471/451-4-7-0-temporary-server-error-please-try-again-later-prx5)
 * *571 5.7.1 Relay access denied*: please double check the username and email address in the advanced identity settings (via the manual setup).
+* *550 5.7.1.You must check for new mail before sending mail ... Local senders are prohibited to send to local recipients without authentication*: did you enter a username/password and did you select either SSL/TLS or STARTTLS in the identity settings? You can try the identity option *Login before sending* (since version 1.2184).
 * Please [see here](https://support.google.com/a/answer/3726730) for more information and other SMTP error codes
 
 If you want to use the Gmail SMTP server to workaround a too strict outgoing spam filter or to improve delivery of messages:

index.html

@@ -993,6 +993,7 @@ Visit https://aka.ms/smtp_auth_disabled for more information.</code></pre>
 <li><em>451 4.7.0 Temporary server error. Please try again later. PRX4 …</em> indicates a server configuration problem, please <a href="https://www.limilabs.com/blog/office365-temporary-server-error-please-try-again-later-prx4">see here</a> or <a href="https://judeperera.wordpress.com/2019/10/11/fixing-451-4-7-0-temporary-server-error-please-try-again-later-prx4/">see here</a>.</li>
 <li><em>451 4.7.0 Temporary server error. Please try again later. PRX5 …</em> indicates a server configuration problem, please <a href="https://www.limilabs.com/qa/4471/451-4-7-0-temporary-server-error-please-try-again-later-prx5">see here</a></li>
 <li><em>571 5.7.1 Relay access denied</em>: please double check the username and email address in the advanced identity settings (via the manual setup).</li>
+<li><em>550 5.7.1.You must check for new mail before sending mail … Local senders are prohibited to send to local recipients without authentication</em>: did you enter a username/password and did you select either SSL/TLS or STARTTLS in the identity settings? You can try the identity option <em>Login before sending</em> (since version 1.2184).</li>
 <li>Please <a href="https://support.google.com/a/answer/3726730">see here</a> for more information and other SMTP error codes</li>
 </ul>
 <p>If you want to use the Gmail SMTP server to workaround a too strict outgoing spam filter or to improve delivery of messages:</p>