Mac Mail trying to send personal domain email via iCloud server

cajunalton wrote:

I have MacBook Pro 14" with M5 chip. I am running Tahoe 26.1 and Mac mail 16. I am experiencing a very frustrating problem. I have four email accounts: icloud, gmail, outlook, and a personal domain. Each accound it setup to use its predefined servers. I use IMAP settings to manage my email. Each outbound is set to their respective service. However, when I try to send mail with personal domain, it attempts to use icloud server with personal domain email user name. I have checked over and over to make sure the outbound server settings were all set to their respective servers. It pops up the window to choose a new server and if I change to the correct one, it works and the email sends. My wife's macbook air 13" with an M1 with Tahoe 26.1 and mac Mail 16 also just starting having this same issue. When the accounts run a status check, everythig is green. Mac mail seems to be unable to keep the username and servers algined properly. All my accounts are online and work after I correct the servers with the pop up and all incoming emails are workling as well. Any ideas would be helpful.

When you compose a message (or reply to one) in Apple Mail, you see the "To, cc, bcc, Subject, and From" lines. The key one for this issue is the "From" line. You should check that it is from the service you want that email to be sent from, not from the "wrong" one. If one of the wrong ones shows, correct it before attempting to send, there is a drop down menu and you can select one of the other account services to make sure the right one is selected, then hit Send.

cajunalton wrote:

I have MacBook Pro 14" with M5 chip. I am running Tahoe 26.1 and Mac mail 16. I am experiencing a very frustrating problem. I have four email accounts: icloud, gmail, outlook, and a personal domain. Each accound it setup to use its predefined servers. I use IMAP settings to manage my email. Each outbound is set to their respective service. However, when I try to send mail with personal domain, it attempts to use icloud server with personal domain email user name. I have checked over and over to make sure the outbound server settings were all set to their respective servers. It pops up the window to choose a new server and if I change to the correct one, it works and the email sends. My wife's macbook air 13" with an M1 with Tahoe 26.1 and mac Mail 16 also just starting having this same issue. When the accounts run a status check, everythig is green. Mac mail seems to be unable to keep the username and servers algined properly. All my accounts are online and work after I correct the servers with the pop up and all incoming emails are workling as well. Any ideas would be helpful.

If no resolve see:

—if you are using Hide My email

Set up and use Hide My Email in iCloud+ on all your devices - Apple Support

—if you are using iCloud Private Relay on Mac - Apple Support

Use iCloud Private Relay on Mac - Apple Support