PHPMailer如此缓慢地连接到SMTP服务器

Question

I'm using PHPMailer to send mail from my webpage. But it's too slow.

SMTPDebug

2015-01-15 23:43:51 Connection: opening to srv1.xxx.net:25, t=30, opt=array ( ) 
2015-01-15 23:43:51 Connection: opened 
2015-01-15 23:46:11 SERVER -> CLIENT: 220-srv1.xxx.net ESMTP Exim 4.84 #2 Fri, 16 Jan 2015 01:46:11 +0200 220-We do not authorize the use of this system to transport unsolicited, 220 and/or bulk e-mail. 
2015-01-15 23:46:11 CLIENT -> SERVER: EHLO localhost 
2015-01-15 23:46:11 SERVER -> CLIENT: 250-srv1.xxx.net Hello localhost [xx.yyy.xx.yyy] 250-SIZE 52428800 250-8BITMIME 250-PIPELINING 250-AUTH PLAIN LOGIN 250-STARTTLS 250 HELP 
2015-01-15 23:46:11 CLIENT -> SERVER: AUTH LOGIN 
2015-01-15 23:46:11 SERVER -> CLIENT: 334 VXNlcmsdsds5hbWU6 
2015-01-15 23:46:11 CLIENT -> SERVER: YmlsZ2lsdAcmVyZXJsdsdsdlsdcmFyYXJhLm5ldA== 
2015-01-15 23:46:11 SERVER -> CLIENT: 334 UGFsdsdzc3dvcmQ6 
2015-01-15 23:46:11 CLIENT -> SERVER: U0ZHdWxlsdsdcis3NDg1 
2015-01-15 23:46:11 SERVER -> CLIENT: 235 Authentication succeeded Connected ok!
2015-01-15 23:46:11 CLIENT -> SERVER: QUIT 
2015-01-15 23:46:11 SERVER -> CLIENT: 221 srv1.xxx.net closing connection 
2015-01-15 23:46:11 Connection: closed 

about 4 minutes.

CENTOS 6.6 x86_64, WHM 11.46.2, Apache/2.2.25 (Unix), PHP 5.4.17

Answer 1

Your server is probably using something called a greetdelay. In the SMTP spec, it's a violation to send anything before the server sends you something, and this is used to spot badly behaved clients (i.e. Spambots) and kick them out. Because this is all happening on the remote server side, there is nothing phpmailer can do about it.

This illustrates that SMTP is not really intended for interactive use. The solution to this is to have a local mail server that you can submit messages to more quickly, and have it do the waiting so you can get on with delivering your page.