Need alternative method of sending by SMTP urgently

Did we ever see any of the sasl related errors? I don't remember seeing anything other than the initial run at the problem.. We really need to see logs to guide you. If it has ever worked, then I can't imagine that it would be all that hard to make it work again...I would imagine there's an error we can work with in the logs.

As for "immediate" solutions...well, no good ones. That's why we all suffer through saslauthd.

You could find out the IP addresses of all of your senders, and add those to the list of local networks. This, of course, won't work for dynamic IP addresses.

POP-before-SMTP was the ancient way of solving this problem...but I haven't seen anyone mention it in like fifty years, so I don't even know if there are still maintained packages for doing it.

You could also try compiling the Dovecot SASL authenticator that I mentioned a while back in our conversation. I don't know that it's any easier, but maybe you can find better and more recent documentation? I dunno. I do sympathize...I found saslauthd to be very difficult to setup, and I've been a professional system administrator for a dozen years now (the sad thing is, it's usually a total of four or five lines of configuration...but it's spread across three files, and those files are always in bizarre locations).