User-Agent: Mozilla/5.0 (X11; U; Linux i686; de-AT; rv:1.6) Gecko/20040117 Build Identifier: Mozilla/5.0 (X11; U; Linux i686; de-AT; rv:1.6) Gecko/20040117 Mozilla uses the domain part of the identity's email address for EHLO and HELO. However, according to RFC 2821 (and RFC 821), a fully-qualified domain name identifying the domain name should be used, see 4.1.1.1 Extended HELLO (EHLO) or HELLO (HELO). The RFC also says: >> - The domain name given in the EHLO command MUST BE either a primary host name (a domain name that resolves to an A RR) or, if the host has no name, an address literal as described in section 4.1.1.1. << So I think it would be correct to: * make a connection to the SMTP server * use getsockname() to get the IP address of the interface used to connect * call gethostbyaddr() onto the IP address * if there is a result, use it, else use [ IP address ] What do you think about this? Reproducible: Always Steps to Reproduce:

*** This bug has been marked as a duplicate of 68877 ***

verified.