[Evolution] AUTH LOGIN not working

["Oscar A. Valdez" <oscar valdez-bicard com sv>]

I am running Evolution 1.4.5

My default outgoing mail is configured to use login authentication against my
ISP's SMTP server (iPlanet Messaging Server).

Mails I write contain this header:

X-Evolution-Transport: smtp://myusername;auth=LOGIN mailserver com

When I try to send mail, this is the dialogue between Evolution and the SMTP server:
sending : EHLO [10.5.193.214]
received: 250-mta01
received: 250-8BITMIME
This server supports 8bit MIME
received: 250-PIPELINING
received: 250-DSN
received: 250-XDFLG
received: 250-ENHANCEDSTATUSCODES
This server supports enhanced status codes
received: 250-EXPN
received: 250-HELP
received: 250-SAML
received: 250-SEND
received: 250-SOML
received: 250-TURN
received: 250-XADR
received: 250-XSTA
received: 250-XCIR
received: 250-XGEN
received: 250-XLOOP 71EA245D54E21694ACEB8538CA77D3B7
received: 250-AUTH LOGIN PLAIN
received: 250-AUTH=LOGIN
received: 250-ETRN
received: 250-RELAY
received: 250 SIZE 0
sending : AUTH LOGIN <<mime-encoded-username>>
received: 334 UGFzc3dvcmQ6
sending : <<mime-encoded-password>>
received: 235 2.7.0 LOGIN authentication successful.
sending : EHLO [10.5.193.214]
received: 250-mta01
received: 250-8BITMIME
This server supports 8bit MIME
received: 250-PIPELINING
received: 250-DSN
received: 250-XDFLG
received: 250-ENHANCEDSTATUSCODES
This server supports enhanced status codes
received: 250-EXPN
received: 250-HELP
received: 250-SAML
received: 250-SEND
received: 250-SOML
received: 250-TURN
received: 250-XADR
received: 250-XSTA
received: 250-XCIR
received: 250-XGEN
received: 250-XLOOP 71EA245D54E21694ACEB8538CA77D3B7
received: 250-AUTH LOGIN PLAIN
received: 250-AUTH=LOGIN
received: 250-ETRN
received: 250-RELAY
received: 250 SIZE 0
sending : MAIL FROM:<oscar example-domain1 com>
received: 250 2.5.0 Address Ok.
sending : RCPT TO:<oscar valdez example-domain2 com>
received: 550 5.7.1 Relaying not allowed: oscar valdez example-domain2 com
sending : QUIT
received: 221 2.3.0 Bye received. Goodbye.

After getting the response to the first EHLO, Evolution authenticates
succesfully, then sends a second EHLO, after which it doesn't authenticate, and
the messages get bounced.

Any clues on how to solve this will be greatly appreciated.
-- 
Oscar A. Valdez

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