I am getting a SMTP 500 Syntax error.

Over the last few years, more and more ISP's have started to block 3rd Party SMTP.  The ISP's require their subscribers to use their SMTP server to send email.  This allows them to monitor spammers.

If you are getting a "Cannot Connect to mail.mydomain.com" SMTP error, check on the list below for your ISP or perform the test listed.  Provided with each ISP that blocks is their respective SMTP server setting.

This list has been compiled by the Doteasy Support staff over the last years.  It is not an official release of ISPs that blocks 3rd Party SMTP, however, it is as accurate as posible at this time.

Testing SMTP server access:

1. Access a command line.

a)    Windows: Click Start -> Run, and then type in CMD
b)    MAC: use the Terminal application in the Applications/Utilities folder

2. Type in telnet mail.YourDomain.com 25

*Replace YourDomain.com with your actual domain name.

3. If you are not being blocked by your ISP, you should see the following message:

220 yourmailserver.doteasy.com (IMail 8.05 807433-10) NT-ESMTP Server X1

If you do not see this message, your ISP is very likely blocking the ability to send mail through servers other than theirs.

Which Canadian ISPs are known to block Port 25?
•    Bell - smtp10.bellnet.ca
•    Sympatico - smtp1.sympatico.ca
•    Rogers - smtp.broadband.rogers.com
•    Shaw - Shawmail
•    Telus - please check with ISP
•    Netcom: smtp.netcom.ca

Which USA ISPs are known to block Port 25?
•    AOL: smtp.mail.aol.com
•    AT&T: mailhost.att.net
•    AT&T Global: smtp1.attglobal.net
•    Bell south: mail.bellsouth.net
•    Comcast: smtp.comcast.net
•    Cox West: smtp.west.cox.net
•    Cox Central: smtp.central.cox.net
•    Cox East: smtp.east.cox.net
•    Cox Business: smarthost.coxmail.com
•    DCANET: smtp-relay.dca.net
•    Earthlink: mail.earthlink.net or smtp.earthlink.net
•    Mindspring: smtp.mindspring.com
•    MSN: smtp.email.msn.com
•    Netcom: smtp.ix.netcom.com        
•    NetZero: smtp.netzero.net
•    Pacific Bell (Pacbell): mail.pacbell.net
•    Prodigy: mtp.prodigy.net
•    RoadRunner: smtp-server..rr.com
•    Verio: smtp.veriomail.com
•    Verizon: outgoing.verizon.net or smtpout.verizon.net

Article Details

Last Updated
4th of July, 2013

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