Platonides wrote:
I'm seeing a number of spam bounces at OTRS, which means that some spammers are using the queue mails as source addresses, at least at the SMTP level. Restricting outgoing servers with SPF would protect servers using SPF from receiving that spam. Which IMHO is much more important than handling the backscatters :)
If anything, I would recommend using DKIM (DomainKeys Identified Mail) rather than SPF. Please see http://www.dkim.org/
--Marcin