Allow AUTH LOGIN mechanism

[aronerben]

Hello, from what I'm seeing currently, only the AUTH PLAIN mechanism is supported in sendmail. It would be very beneficial for us if AUTH LOGIN is also supported, as we are using Microsoft Exchange SMTP servers and they have disallowed AUTH PLAIN back in 2017 apparently.

Thank you!

[mabiede]

@dinosaure we would very much appreciate it if this would be implemented. Is there any update on this?

[dinosaure]

Sorry for the delay, it's on my TODO list, I will probably try an implementation next week.

[dinosaure]

I just dig in into the LOGIN method and it seems an obsolete method (only a draft exists about it: https://datatracker.ietf.org/doc/html/draft-murchison-sasl-login-00). I can implement it but do you have another (better) mechanism available?

[aronerben]

@dinosaure Thanks a lot for looking into it and drafting a PR! Unfortunately, AUTH LOGIN is the only mechanism we can use at the moment. Outlook.com seems to have discontinued support for AUTH PLAIN back in 2017 and most of our infrastructure runs on that. So from what I'm seeing, having AUTH LOGIN support in our OCaml Apps is unavoidable.

[dinosaure]

@aronerben thanks for your reply. I was just wondering if you can use a better mechanism, LOGIN seems highly risky to use. Can you try a connection with my draft? Only bad cases are missing but if you use a good username/password, you should able to send an email now with the LOGIN mechanism.

[aronerben]

@dinosaure

Can you try a connection with my draft?

I haven't been able to get it to work, but I'm assuming I'm doing something wrong, I'll keep looking into it. But I just wanted to answer quickly:

I was just wondering if you can use a better mechanism

Yes, apparently, recently, AUTH NTLM was added. If you deem this to be better, we can also gladly use that. I just don't want the work you've already put in to be redundant :)

[aronerben]

@dinosaure I found the problem, I had forgotten to change the mechanism while using STARTTLS :) The happy path works with LOGIN on your draft!

[dinosaure]

Thanks for you feedback. I will cut a release as soon as I can 👍. About NTLM mechanism, we probably should make an other issue about that (and when I will have the time, I will try to implement it).

[aronerben]

@dinosaure Thanks a bunch for your work 🎆 , I'll make the issue.