ATT.net emails require a secure mail key to be generated in order to allow mail apps to connect.

1. Create a secure mail key in your AT&T account. Visit https://www.att.com/support/article/email-support/KM1240308/ for instructions on creating the secure mail key. 
   • Yahoo email allows a third-party app password: https://help.yahoo.com/kb/generate-manage-third-party-passwords-sln15241.html
2. When the secure mail key or third party app password is generated, write it down or paste it into Notepad and save it on your desktop for convenient access. You will need to use it later.
3. In Sage 50, go to Maintain, Email Setup, and select Use a webmail account.
4. Select Add account information or Edit.
5. For the Webmail Service, select Yahoo and enter your email address. Click OK and then OK again.
6. Email something from Sage 50 such as an invoice.
7. When prompted to enter your email password, use the secure mail key instead. You will need to use this secure mail key every time you are prompted in Sage for your email password.

If the "An unknown error occurred connecting to the SMTP server" error still occurs:

1. Go back to Maintain, Email Setup. Click Edit.
2. For the Webmail Service, select Other.
3. In the SMTP Server, enter smtp.mail.att.net and for the SMTP Port use 465 or 587 (first try one, and if that doesn't work, try the other). Click OK and then OK again.
4. Test by emailing from Sage 50.

If you prefer to use a mail app such as Outlook or Thunderbird, refer to https://www.att.com/support/article/email-support/KM1086159. You will need to set up a secure mail key.

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