Unable to configure authentication emailing

[paulscode]

I am using SMF 1.1.14, and due to an increase in advertisers, I need to require authentication emails for new users.  However neither of the settings in Configuration -> Server Settings -> Feature Configuration -> Mail Type works.

If I choose PHP, when it tries to send out an email, I get the following in the error log:

Koodi [Valitse] Laajenna

Unable to send mail to the email address '[email protected]'

If I choose SMTP instead, when it tries to send out an email, I get the following in the error log instead:

Koodi [Valitse] Laajenna

Ran into problems sending Mail. Error: 503 AUTH command used when not advertised

Anyone have any thoughts on a workaround?

For reference, my host is 1and1, and I'm using the following SMTP settings:

Koodi [Valitse] Laajenna

SMTP Server: smtp.1and1.com
SMTP port: 25
SMTP username: [email protected]
SMTP password: mypassword

I've also tried using SMTP port 587 as suggested on another thread I saw, but that didn't work for me.  In that case it spit out a different message in the error log:

Koodi [Valitse] Laajenna

2: fsockopen() [<a href='function.fsockopen'>function.fsockopen</a>]: unable to connect to smtp.1and1.com:587
File: [path]/Subs-Post.php
Line: 973

[Illori]

you need to contact your host and have them verify the connection information for the smtp.

[paulscode]

Well, I know the connection information is correct, because I used it to setup my personal email client (same server, port, username, and password).  I will try and get in touch with them to see if they have any suggestions.  However, from the error message "AUTH command used when not advertised", I would guess there is a problem with the way the code is setting up the outgoing email (may require me to apply a modification to the code, I'm thinking).