One connection per sender

Each From address is used by one connection, active or inactive — a message from that address always goes out through the connection that owns it.

• Capitals don’t matter: Hello@example.com and hello@example.com are the same address.
• hello+backup@example.com is a different address from hello@example.com.
• A connection with no From address of its own never conflicts with another one.

When BooleanSMTP refuses to save a connection

Saving or activating a second connection with an address another one already uses is refused, naming the connection that owns it. To fix it:

1. Open the connection the message names and change its provider there, or
2. Give one of the two connections a different From address.

Next steps

• How a connection is chosen
• Mailers
• Troubleshooting