CFMAIL failed and retried despite 250 from SMTP server

Hi,

I’ve stumbled upon a strange issue with sending an email in Lucee 4.5.1.000.
The initial sending job failed and was placed into the Task Manager to be
re-tried.

All attempts but one failed with this error message:

smtp.*****.com timeout occurred after 30 seconds while sending mail message
javax.mail.MessagingException: timeout occurred after 30 seconds while
sending mail message at lucee.runtime.net.smtp.SMTPClient._send(Unknown
Source) at lucee.runtime.spooler.mail.MailSpoolerTask.execute(Unknown
Source) at lucee.runtime.spooler.SpoolerTaskSupport._execute(Unknown
Source) at lucee.runtime.spooler.SpoolerEngineImpl.execute(Unknown Source)
at lucee.runtime.spooler.SpoolerEngineImpl$TaskThread.run(Unknown Source) :0

smtp.*****.com timeout occurred after 30 seconds while sending mail message
javax.mail.MessagingException: timeout occurred after 30 seconds while
sending mail message
at lucee.runtime.net.smtp.SMTPClient._send(Unknown Source)
at lucee.runtime.spooler.mail.MailSpoolerTask.execute(Unknown
Source)
at lucee.runtime.spooler.SpoolerTaskSupport._execute(Unknown Source)
at lucee.runtime.spooler.SpoolerEngineImpl.execute(Unknown Source)
at lucee.runtime.spooler.SpoolerEngineImpl$TaskThread.run(Unknown
Source)
:0
at lucee.runtime.net.smtp.SMTPClient._send(Unknown Source):-1
at lucee.runtime.spooler.mail.MailSpoolerTask.execute(Unknown
Source):-1
at lucee.runtime.spooler.SpoolerTaskSupport._execute(Unknown
Source):-1
at lucee.runtime.spooler.SpoolerEngineImpl.execute(Unknown
Source):-1
at lucee.runtime.spooler.SpoolerEngineImpl$TaskThread.run(Unknown
Source):-1

One attempt, however, failed with this message:

smtp.*****.com 250 2.1.5 Recipient OK at
com.sun.mail.smtp.SMTPTransport.issueSendCommand(SMTPTransport.java:1333):1333
at com.sun.mail.smtp.SMTPTransport.data(SMTPTransport.java:1152):1152 at
com.sun.mail.smtp.SMTPTransport.sendMessage(SMTPTransport.java:537):537 at
lucee.runtime.net.smtp.SMTPSender.run(Unknown Source):-1 :0

smtp.*****.com 250 2.1.5 Recipient OK

    at 

com.sun.mail.smtp.SMTPTransport.issueSendCommand(SMTPTransport.java:1333):1333
at
com.sun.mail.smtp.SMTPTransport.data(SMTPTransport.java:1152):1152
at
com.sun.mail.smtp.SMTPTransport.sendMessage(SMTPTransport.java:537):537
at lucee.runtime.net.smtp.SMTPSender.run(Unknown Source):-1
:0
at
com.sun.mail.smtp.SMTPTransport.issueSendCommand(SMTPTransport.java:1333):1333
at
com.sun.mail.smtp.SMTPTransport.data(SMTPTransport.java:1152):1152
at
com.sun.mail.smtp.SMTPTransport.sendMessage(SMTPTransport.java:537):537
at lucee.runtime.net.smtp.SMTPSender.run(Unknown Source):-1

Interestingly, the attempt that failed with the above message still
regardless of the 250 response from SMTP.

Is it correct to assume that the only explanation for the above failed
message is that communication with the SMTP server did not complete before
the timeout (using default 30 seconds value) was reached?

Thank you so much for any response!

Best regards,
Max