Go to options of settings. Enter the options passwords & account and choose the options of add account. Enter the options of others if the option of ATT email not available. Enter the options of add mail and provide the required information. Enter the options of IMAP and complete out the IMAP settings that have been provided above. Enter the button of next Enter the button of save. 993 is the server port number of incoming server. 465 is the server port number of outgoing server. Enter the button of done and restart your iPhone. Above mentioned are the best ATT IMAP Settings for iPhone .
See Also this post;- https://datarecovo.educatorpages.com/pages/att-net-mail-settings-for-outlook