SMTP AUTH not bypassing SPF

[xannonite]

After upgrading from Plesk 9.2 to 9.3, I can no longer send messages from Thunderbird using port 587 if SPF spam protection is enabled on the server. I receive this error:

mail server permanently rejected message (#5.3.0)

All of the settings in Plesk are exactly as they were before the upgrade. Attached is a screenshot of the settings. Turning SPF spam protection off in Plesk allows me to send messages. Here is an excerpt from the maillog:

qmail-queue-handlers[5900]: Handlers Filter before-queue for qmail started ...
qmail-queue-handlers[5900]: from=me@mydomain.com
qmail-queue-handlers[5900]: to=someone@theirdomain.com
qmail-queue-handlers[5900]: hook_dir = '/usr/local/psa/handlers/before-queue'
qmail-queue-handlers[5900]: recipient[3] = '****'
qmail-queue-handlers[5900]: handlers dir = '/usr/local/psa/handlers/before-queue/recipient/someone@theirdomain.com'
qmail-queue-handlers[5900]: found handlers entry = '/usr/local/psa/handlers/before-queue/global/10-spf-cOFuh3'
qmail-queue-handlers[5900]: call_handlers: call executable = '/usr/local/psa/handlers/info/10-spf-cOFuh3/executable'
spf filter[5901]: Starting spf filter...
qmail-queue-handlers[5900]: handlers_stderr: REJECT
qmail-queue-handlers[5900]: call_handlers: REJECT during call '/usr/local/psa/handlers/info/10-spf-cOFuh3/executable' handler
qmail-queue-handlers[5900]: call_handlers: stop call handlers from dir '/usr/local/psa/handlers/before-queue/global'

I have SPF records configured for all of my domains that only allow the MX record to send mail. However, mail sent from a PC using a client such as Thunderbird has the PC's address, not the server's. Sending through port 587 had been bypassing this issue up until 9.3. If anyone can shed some light on the situation, I'd be much obliged.

 

[SoheylM]

Same problem here.