There are plenty errors related to Mail SMTP Sending failed: MCMailErrorDomain error 1045MCMailErrorDomain error 1046MCMailErrorDomain-Fehler 1045, MCMailErrorDomain-Fehler 1030…Whatever your problem is, look at the following 2 ways to fix.

MCMailErrorDomain error 1045, 1046

I, Fix MCMailErrorDomain error with Credentials

This solution is simple but somehow works. Users need to re-provide the SMTP server, email address and the password in the Mail app preferences.

  • Launch Mail Application in Mac OS X, then access ‘Preference’. You then are able to select ‘Account’ tab.
  • Select the affected mail account in trouble, then click on ‘Outgoing Mail Server (SMTP)’.
  • Choose ‘Edit SMTP Server List’, then select ‘Advanced’ from the Edit SMTP Server List window.
  • What should do is re-fill your email address and password of account experiencing error, then click on OK.

Re-enter login and password to fix MCMailErrorDomain error

Your problem now should be solved. Otherwise, take the second solution:

II, Manually fix MCMailErrorDomain error

Whatever error you face (1045, 1046, 1030, etc…), you can get rid of trouble by the following steps:

  • Firstly, you need to quit the mail application in OS X.
  • Access “Go to folder” by pressing Command+Shift+G together then Copy and paste this code: ~/Library/Mail/V2/MailData/
  • You are going to modify the Accounts.plist file, so you should copy a backup file to somewhere in the desktop first.
  • Open “Accounts.plist” using a text editor, then search the following lines:

<key>UserAllowsInsecureAuthentication</key>
<false/>

  • Change <false/> to <true/>

Edit Accounts.plist to fix mail error in os x

Close the text editor, save the change, and then check to see if the error is fixed.

The 2 above solutions probably fix all common error related to Mail app in Mac OS X such as MCMailErrorDomain error 1045MCMailErrorDomain error 1046MCMailErrorDomain-Fehler 1045 and MCMailErrorDomain-Fehler 1030.

Best luck!

  • Antonio

    it works, also you need restart Mail