Updated FAQ

FAQ.md

@@ -715,6 +715,9 @@ There are general errors and errors specific to Gmail accounts (see below).
 The error *... Authentication failed ...* likely means your username or password was incorrect.
 Some providers expect as username just *username* and others your full email address *username@example.com*.
 
+The errors *... invalid greeting ...*, *... requires valid address ...* and *... Parameter to HELO does not conform to RFC syntax ...*
+can likely be solved by changing the advanced identity setting *Use local IP address instead of host name*.
+
 The errors *... Couldn't connect to host ...*, *... Connection refused ...* or *... Network unreachable ...*
 mean that FairEmail was not able to connect to the email server.