Articles

IMAP, POP3 configurations, SMTP server-client communication

• Configuring POP3 for Remote Mailboxes and Applying Sorting Rules in Kerio Connect

  Overview Kerio Connect can retrieve messages from remote mailboxes via POP3 (Post Office Protocol Version 3). A scheduled action triggers the retrieval, and the sorting rules process the downloaded me...

• 451 Temporary local problem - please try later while sending/receiving emails

  Overview Users are getting a Non-Delivery Receipt (NDR) email with the following error messages: <xxxx@testmail.com> (<server name> 451 Temporary local problem - please try later) 4.1.1 451 Temporaril...

• Securing the Kerio Connect SMTP Server

  Overview The Kerio Connect SMTP server has built-in settings to secure the email messages' connection. Misconfigured SMTP may produce the following error in Security logs: SMTP connection from x.x.x.x...

• Error: 'Cannot connect to SMTP server...' - Kerio Connect

  Overview   Sometimes users report that their emails are not getting sent to external mail servers, domains, or recipients. The warning log shows dozens of entries similar to this:   [14/Jul/2019 14:50...

• Error: "4.5.3 Too many recipients, maximum recipient count exceeded" When Sending Emails

  Overview You may receive similar non-delivery emails (NDR) with the following message: 4.5.3 Too many recipients, maximum recipient count <number> exceeded. This article explains why this error occurs...

• Sending Kerio Connect Emails Through SMTP Outbound Relay

  Overview When there is a need to configure SMTP outbound relay (Mail Gateway), the specific Kerio Connect settings in SMTP Delivery should be applied. As an example, the process below covers using SMT...

• Resolving the Error: 'Status: 4.3.0 Recipient's mailbox busy'

  Overview When a resource is tied up and cannot be used by another part of the mailserver process, the following error is shown in the Mail logs. Status: 4.3.0 Recipient's mailbox busy   As a result, t...

• Email Domain Forwarding

  Overview When setting up the Kerio account via an external mail server, the Domain forwarding needs to be configured. Kerio Connect uses login credentials defined in the SMTP relay server settings for...

• MXtoolbox Domain Health problems

  Overview While performing the MXtoobox domain check, the tool returns the response about problems with SMTP Banner, Reverse DNS mismatch, SMTP TLS, and transaction time. These settings can be checked ...

• Debugging Internal Email sending and routing

  Overview While trying to configure Kerio Connect accounts to work concurrently with external providers such as O365, Gmail, etc, the message sending and receiving is not working for both providers tog...