All articles · Page 4
Who Is Actually Delivering to Your Tenant? Aggregating Sending IP Addresses
A single report shows which systems actually deliver mail to your tenant: forgotten connectors, applications sending directly, and service providers nobody documented, including the typical analysis errors involving pagination logic and interpretation.
Common Causes of Mail Loops and How to Fix Them
How to systematically identify and fix SMTP mail loops in Exchange Online, hybrid environments, and upstream mail gateways using NDRs, headers, Message Trace, recipient objects, and connectors.
EXO Migration Without a Remote Move
How to provision on-premises Exchange mailboxes in a controlled manner as new, empty Exchange Online mailboxes: PST backup, CSV approval, RemoteMailbox, synchronization, validation, and rollback.
Guide for DNS Administrators: MX, SPF, DKIM, DMARC, and Common Pitfalls
Anyone managing a zone will usually receive ready-made mail records and only needs to publish them. What regularly goes wrong: the 255-byte limit for DKIM, duplicate SPF records, the lookup limit, MX pointing to a CNAME, automatically appended zone suffixes, and policies nobody enforces anymore.
Renewing a Certificate on the Cisco SMA
Certificates can only be installed on the Cisco SMA through the CLI, and current AsyncOS versions validate the entire chain during import: without a stored root CA, the import fails. This article shows the paths to a new key pair, the OpenSSL approach in detail, how to handle OpenSSL 3's RC2-40-CBC error, and how to import the internal root CA into the appliance's trust store.
HIN Platform Renewal 2026: Access Gateway, Client, and Deadlines Through September 14
Firewall approval by August 14, Access Gateway version 4 from August 17, SAML endpoints, hardware tokens, and HIN Client by September 14. The mail gateway is not affected and will be replaced separately.
Testing SMTP on Linux: From the TCP Connection to Delivered Email
When an appliance stops delivering email, a manual SMTP test is more useful than any log. Learn how to check each layer using built-in tools, what different error patterns mean, and why a load balancer can distort diagnosis.
Microsoft Entra Domain Services: LDAP and Kerberos for Cloud-Only Environments
Entra ID does not speak LDAP or Kerberos. Microsoft Entra Domain Services provides a managed Active Directory domain that synchronizes users from Entra ID and offers traditional protocols. How it works, limitations, costs, and a real-world email gateway use case.
Connect the SEPPmail Admin GUI to Active Directory: Configure LDAP Authentication Starting with 15.0.6
Starting with firmware 15.0.6, administrators of the SEPPmail appliance can authenticate against an external LDAP server such as Active Directory, including group mapping to the local admin group. Configuration under User > Advanced Settings, step by step.
SEPPmail 15.0.6 and 15.0.6.1: Security Fixes and New Admin Features
In July 2026, SEPPmail released patch release 15.0.6 and hotfix 15.0.6.1. In addition to fixing vulnerabilities in PDF generation and PGP processing, the releases introduce a separate MFA field, LDAP authentication for the Admin GUI, and fixes for RuleEngine, webmail, and the REST API.
Running Paperless-ngx with Limited Storage: Offload Documents to a Cloud Service
Paperless-ngx only needs the database, search index, and thumbnails locally; the documents themselves can reside in a cloud service. What the practical test showed and how to set it up with the ready-made template in three commands.
Proton Drive on Linux: Status as of July 2026
The official Linux client has been announced but is not yet available. On servers, Proton Drive can currently be mounted with Rclone; the new SDK indicates the technical direction. What is still missing is machine access limited to individual folders or tasks.
