Smtp.Send two times at once (<1s difference) problem

0 votes
asked Jul 17, 2015 by dirk (530 points)


today a rather strange problem occured:
I tried to send two mails with less than 1s difference in time; while the first got sent correctly, the second didn't receive, I ended up with the following exception:
"One or more recipients rejected. Call SmtpException.GetRejectedRecipients() to get a collection of rejected email addresses.”

Is time an issue here? Do I need to wait between a sending period? If yes, how could I implement a valid routine to allow the correct sending process of both mails.


Applies to: Rebex Secure Mail

1 Answer

0 votes
answered Jul 17, 2015 by Lukas Pokorny (128,250 points)

Time does not matter to the Smtp object, so this is most likely a server issue. Could you please create a communication log showing both successful and unsuccessful attempts and either post them here or mail them to us for analysis? That should make it possible to tell why the server is rejecting the message.

Also, please note that the array returned by SmtpException.GetRejectedRecipients() contains a list of rejected addresses along with SMTP server responses, and those are likely to contain additional information as well (the same as the log).

commented Apr 6, 2017 by Lukas Pokorny (128,250 points)
Sorry, we don't routinely backport hotfixes to older releases. Please use the official workaround code instead:
commented Apr 6, 2017 by dsouzac (420 points)
ok but let us know for latest version hotfix.
commented Apr 17, 2017 by dsouzac (420 points)
is this hot fix is included in your's latest release Rebex 2017 R2? or when it will be available?
commented Apr 17, 2017 by Lukas Pokorny (128,250 points)
The hotfix will be released with Rebex Secure Mail 2017 R3. In the meantime, please use the workaround Send method from
commented May 10, 2017 by Lukas Pokorny (128,250 points)
We have released Rebex Secure Mail / Rebex Total Pack 2017 R3 that incorporates this hotfix: Thanks for bringing this issue to our attention.