Apple Mail (macOS) with ImprovMX SMTP

Note: You must be a paid subscriber to use ImprovMX SMTP.

This guide sets up macOS Mail to read forwarded mail from Gmail over IMAP and send from an address on your custom domain — like [email protected] — through ImprovMX SMTP.

Prerequisites

Step 1: Add the account

In the Mail app, go to Mail > Add Account, select Other Mail Account…, and click Continue.

Pick Other Mail Account…, not the Google option. Mail's Google auto-setup locks the sending server, so you can't switch it to ImprovMX SMTP.

The Mail account provider picker with Other Mail Account… highlighted The Mail account provider picker with Other Mail Account… highlighted

Step 2: Enter account info

  • Name: Display Name
  • Email Address: ImprovMX sending alias (e.g. [email protected])
  • Password: Gmail App Password

Click Sign In. It will likely say it can't verify the account — that's expected.

Mail's Add Account sheet with the name, custom-domain email, and password filled in Mail's Add Account sheet with the name, custom-domain email, and password filled in

Step 3: Enter mail server details

  • Email Address: ImprovMX sending alias (e.g. [email protected])
  • Username: your Gmail address
  • Password: Gmail App Password
  • Account Type: IMAP
  • Incoming Mail Server: imap.gmail.com
  • Outgoing Mail Server: smtp.improvmx.com

Click Sign In again. You'll likely get the same verification warning — click Next to continue.

Mail's mail-server sheet filled with imap.gmail.com for incoming and smtp.improvmx.com for outgoing Mail's mail-server sheet filled with imap.gmail.com for incoming and smtp.improvmx.com for outgoing

Step 4: Finish account setup

Leave only Mail checked, then click Done. You now have a working IMAP account with Gmail as the backend.

Mail's services sheet with only Mail checked Mail's services sheet with only Mail checked and Notes unchecked

Step 5: Set the outgoing server

Go to Mail > Settings > Accounts, select your account, and open the Server Settings tab.

Leave the incoming server as-is. Under Outgoing Mail Server (SMTP), set:

  • Username: your ImprovMX SMTP credential username (e.g. [email protected])
  • Password: your ImprovMX SMTP credential password
  • Host Name: smtp.improvmx.com
  • Uncheck Automatically manage connection settings
  • Port: 587
  • Check Use TLS/SSL
  • Authentication: Password

Click Save.

Use TLS/SSL is Mail's label for STARTTLS on port 587. If your network blocks that port, use 465 instead, which connects over SSL/TLS directly — either works.

The Accounts settings pane with the outgoing server set to smtp.improvmx.com on port 587 with TLS/SSL on The Accounts settings pane with the outgoing server set to smtp.improvmx.com on port 587 with TLS/SSL on

Step 6: Send a test

Send a message from your alias to another address you own.

If macOS shows "Can't connect to account", re-enter your ImprovMX SMTP credential password and click OK — it won't ask again.

That's it. macOS Mail now sends from your custom domain via ImprovMX SMTP and receives over Gmail IMAP.

Sending from more than one address

The above setup sends from one address only — say [email protected]. Anything else in the From field won't send.

To send from every address on your domain — [email protected], [email protected], and the rest — swap in an any alias credential. You can then send from multiple addresses on the domain using only one set of credentials.

In Apple Mail you can also send from your Gmail address or a second domain, but each needs its own outgoing server — so you switch servers for every message. Thunderbird pairs each address with its server, so you don't have to.

Questions? Reach out — we're happy to help.