SMTP Routing · Exchange Add-on v3.2.4

MultiSendcon

Multiple Send Connectors for Exchange — Based on Sender

Microsoft Exchange routes all outgoing mail through a single SMTP relay. MultiSendcon breaks that constraint: route each sender's outbound email through the correct relay server, with the right credentials — automatically.

30-day full-featured trial
Per-server license, one-time fee
Exchange 4.5 – 2019 + SE supported
When You Need It

Common scenarios

Multiple companies, one server

You host Company A and Company B on the same Exchange. Each company uses a different mail provider. MultiSendcon routes each domain through the correct relay — automatically.

Mix corporate and Google Workspace addresses

Staff use both @company.com (Exchange) and @gmail.com (Google Workspace) addresses. MultiSendcon sends the Google addresses through Gmail's SMTP relay so authentication works correctly.

IP reputation management

Route high-volume bulk mail through a dedicated IP or provider while keeping transactional mail on your primary relay. Protect your main IP's sender reputation.

Capabilities

What MultiSendcon does

Routes each outgoing message to a different SMTP relay server based on who sent it. Configure unlimited routing rules — by sender email address, domain, or wildcard pattern.

Each routing rule carries its own SMTP relay login credentials. One sender can authenticate to Office 365, another to your ISP, a third to a dedicated transactional mail service — all from the same Exchange server.

All relay connections use TLS encryption. Supports STARTTLS and implicit TLS (port 465 / 587) for every configured outbound route.

Bind outgoing connections to specific local network interface IP addresses per sender. Required when you need outgoing mail from different IPs for deliverability or compliance reasons.

Host multiple companies or domains on a single Exchange server and route each domain's outgoing mail through the correct relay — different provider, different credentials, fully isolated.

Route mail based on the recipient domain in addition to sender address. Useful when a specific destination requires a dedicated relay or authentication.

Works with every version of Exchange Server ever released — through Exchange Server SE (Subscription Edition) — including all Small Business Server editions. No Exchange Online requirement.

The LITE edition (single relay account, no per-sender routing) is bundled free. Useful for Exchange 2003 and earlier when SSL support for outbound SMTP is needed without the full multi-account feature set.

Editions

MultiSendcon vs MultiSendcon LITE

Choose the edition that matches your environment.

MultiSendcon
Full Version
Recommended
  • Unlimited routing rules by sender
  • Per-sender SMTP credentials
  • TLS 1.2 / 1.3 support
  • Local IP address selection per sender
  • Recipient-dependent routing
  • Multi-domain / multi-company support
  • 30-day free trial
MultiSendcon LITE
Included Free
Bundled
  • Single relay account
  • SSL / TLS support for outbound SMTP
  • Useful for Exchange 2003 and earlier
  • Multiple routing rules
  • Per-sender credentials
  • IP address selection
Support & FAQ

Common questions

How does MultiSendcon decide which relay server to use?

MultiSendcon intercepts outbound Exchange email before it leaves the server and matches the sender address against your configured routing rules. The first matching rule determines which SMTP relay server and credentials to use. Rules can match by exact address, domain, or wildcard pattern.

Can I route email from different departments through different SMTP accounts?

Yes. Configure one rule per department's sender domain or address pattern. For example: sales@company.com → Office365 SMTP, info@anotherdomain.com → Gmail SMTP. Each rule has its own credentials, TLS settings, and relay server address.

Does MultiSendcon work with Office 365 or Google Workspace?

Yes. Configure an SMTP account pointing to smtp.office365.com (port 587, STARTTLS) or smtp.gmail.com (port 587) with the appropriate credentials. Sender-address-based rules then route each email through the correct provider's relay. If you see "504 5.7.4 Unrecognized authentication type" with Office 365, see our Knowledge Base for the connector configuration fix.

What happens to emails that don't match any routing rule?

Emails that don't match a specific rule fall through to the "Master Relay" configuration — a default SMTP relay used for all unmatched senders. You can also configure MultiSendcon to pass unmatched emails directly to Exchange's built-in send connectors.

How do I install the Exchange Send Connector?

The MultiSendcon installer can automatically create the Exchange Send Connector that routes outbound mail through MultiSendcon. If your environment requires manual setup (e.g., PowerShell remoting is disabled), see our Knowledge Base article "How to manually create the Send Connector in Exchange".

What Exchange versions are supported?

Exchange 2003 through Exchange 2019 and Exchange Server SE. MultiSendcon installs as a Windows service and integrates with Exchange's Send Connector framework — it does not require Exchange agents or transport pipeline plugins.

Release History

Version history

2026
v3.2.4For out-of-office messages Exchange sends with empty SMTP envelope sender, MultiSendcon now replaces the empty sender with the MAIL FROM header field.
v3.2.3VC++ Library v14+ detection now works correctly. New SendConnector installation now works even with PowerShell remoting disabled.
2025
v3.2.2VC++ Library detection improved for newer Windows Server installations. Admin/service communication no longer on a fixed address to avoid conflicts.
v3.2.1New SMTP component for improved TLS compatibility. New Administrator internals logfile with more diagnostic information.
2024
v3.2.0Shows all recipients of a multi-recipient message instead of just the first.
v3.1.9Better error messages for multi-line SMTP server error responses.
v3.1.7Bugfix: Password encryption method incompatible with FIPS-compliant servers replaced with AES encryption.
v3.1.1Newest SMTP components fixing '220 2.0.0 SMTP server ready' error with Office 365.
2021
v2.98TLS 1.2 and TLS 1.3 support.
2015–2016
v2.93Correctly shows first line of multi-line SMTP error messages.
v2.83New: Replace SMTP envelope sender (MAIL FROM) with fixed sender email.
v2.82Passwords now stored encrypted (AES) in configuration file.
v2.80Emails to multiple recipients no longer split into individual emails.
2013–2014
v2.60New: Multithreading for multiple simultaneous outgoing emails.
v2.00Automatically removes temporary X-MultiSendcon header fields before sending.
v1.90First public release.

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