问在Ubuntu18.04LTS上安装sagemath后出现的问题

EN

Package configuration


Postfix Configuration                                                             │ 
  │ Please select the mail server configuration type that best meets your     
  │ needs.                                                                    
  │                                                                           
  │  No configuration:                                                        
  │   Should be chosen to leave the current configuration unchanged.          
  │  Internet site:                                                           
  │   Mail is sent and received directly using SMTP.                          
  │  Internet with smarthost:                                                 
  │   Mail is received directly using SMTP or by running a utility such       
  │   as fetchmail. Outgoing mail is sent using a smarthost.                  
  │  Satellite system:                                                        
  │   All mail is sent to another machine, called a 'smarthost', for          
  │ delivery.                                                                 
  │  Local only:             
No configuration:                                                        
  │   Should be chosen to leave the current configuration unchanged.          
  │  Internet site:                                                           
  │   Mail is sent and received directly using SMTP.                          
  │  Internet with smarthost:                                                 
  │   Mail is received directly using SMTP or by running a utility such       
  │   as fetchmail. Outgoing mail is sent using a smarthost.                  
  │  Satellite system:                                                        
  │   All mail is sent to another machine, called a 'smarthost', for          
  │ delivery.                                                                 
  │  Local only:                                                              
  │   The only delivered mail is the mail for local users. There is no        
  │ network.                                                                  
  │                                                                           
  │                                 <Ok>