If you cannot send email through Optimum Online (Optonline) or another Internet Service Providers (ISPs) and you are receiving an error message which states something such as “Cannot send outgoing mail due to Port 25 being blocked”, this usually indicates a problem with your Internet Service Provider (ISP) and NOT your web host or Bower Web Solutions itself.

What Is Port 25 and why is it being blocked?

To help control the amount of spam and viruses that originate from your ISP (like Optimum Online or Earthlink, etc.) your Internet Service Provider may start to implement outbound Port 25 (SMPT) filtering. Filtering Port 25 is a common spam control measure used by Internet Service Providers and the advantages far outweigh the disadvantages when it comes to the war on spam. However, these efforts will not necessarily protect yourself from being flooded with spam.

How can I send my e-mail if my ISP is blocking Port 25?

  • Send via Port 587: Many ISP’s (including the two biggest in Northern New Jersey and the New York City Metro area, Verizon and Optonline) allow you to send e-mail using your outgoing account through Port 587. Sending through Port 587 is especially convenient for laptop users who use multiple ISPs.
    Bower Web Solutions recommends that all of it’s clients use port 587.
  • If you cannot use port 587 and you don’t want to change to Bower Web Solutions hosting:
    Change outgoing mail server to your ISP’s:
    You can change your OUTGOING mail server (SMTP) from “mail.yourdomain.com” or “yourdomain.com” to a SMTP mail server provided by your ISP.
  • For more information on why Port 25 may be blocked, try visiting the Verizon website or the Optimum Online website.

See the list below of leading Internet Service Providers and┬átheir Corresponding SMTP (Simple Mail Transfer Protocol) or “Outgoing Mail Server” settings

For example, Optimum Online now require their internet customers use the following SMTP mail server to send out mail on their network:

mail.optonline.net

If you already have your e-mail program (such as Microsoft Outlook, Mac Mail, etc) you do not need to recreate your e-mail account information again. You simply need to edit the existing account and change the SMTP server for the account(s). After you have entered your IPS’s SMTP server, you will will then need to click on the ‘more settings” tab and go to the “Outgoing Server” tab. On this tab, click on the “Log on using” radio button and enter your user name and password AS PROVIDED BY YOUR INTERNET SERVICE PROVIDER or ISP. (Note: this is NOT your Bower Web Solutions user ID and password).

  1. IMPORTANT NOTE:
    Be aware that many Internet Service Providers (ISP) such as Optimum Online, Verizon, Comcast are now cracking down of “spam activity”. These ISPs are now limiting how many e-mails you can send out from your computer’s location within a given time period and may suspend your ability to send e-mail if you are sending more than 30 recipients at a time or more than 50 separate e-mails within an hour.

If you plan to send large numbers of mass e-mails to your client base, you really need to consider a separate service such as Constant Contact. For less than 75 cents a day, you can take advantage of advanced e-mail tracking features and sleep at night know that your web site or web server will not be “blacklisted” by the major ISPs!

SETTING THE OUTGOING SERVER TO YOUR ISP’s in OUTLOOK OR LIVE MAIL:

  1. Go to the Tools menu and choose “Accounts…”
  2. From the Mail tab, choose your e-mail account and click the “Properties” or “Change” button
  3. In the following window, click on the Servers tab
  4. Change the Outgoing mail (SMTP) server setting to:
    mail.optonline.net
    Note: If your ISP is NOT Optimum Online, then you will need to set your SMTP to a different server. Please contact your ISP directly for more details.
  5. Finally click on the “More Settings” button and enter your ISP username/password in the “Log on Using” section.
  6. Test account Settings (from the general tab or by clicking OK to return to the main window).
  7. If you get the error “None of the authentication methods supported by this client are supported by your server”, uncheck my outgoing server requires authentication. As of early 2009, OptOnline was not requiring that you sign into an account, but merely that you send out using their outgoing mail server.

 

List of Internet Service Providers and Their Respective SMTP or Outgoing Mail Server Settings

Problems Sending E-Mail Using Optimum Online or SMTP Settings for Optonline and other ISPs

If Your Internet Service Provider (ISP)
or Phone Carrier is:
Your STMP Server or “Outgoing Mail Server”
Address would be:
Adelphiamail.adelphia.net
America Online (AOL)smtp.aol.com
Atlantic Broadbandsmtp.atlanticbb.net
AT&T (Broadband)mail.attbi.com
AT&T (Dialup)smtp1.attglobal.net
AT&T Worldnetmailhost.worldnet.att.net or imailhost.worldnet.att.net
BCPLmail.bcpl.net
Bellatlanticgtei.bellatlantic.net or smtpout.verizon.net
Bellatlantic.netsmtpout.bellatlantic.net
Bellsouthmail.bellsouth.net
Bestwebsmtp.bestweb.net
Blazenetsmtp.blazenet.net
Cable Onemail.cableone.net
CAISsmtp.cais.net
CAPUsmtp.capu.net
Charm.netsmtp.charm.net
Charter Communicationssmtp.charter.net
Comcastsmtp.comcast.net
Compuservesmtp.compuserve.com or smtp.site1.csi.com
Concentric.netsmtp.concentric.net
Covadsmtp.covad.net
Cox Westsmtp.west.cox.net (west coast users)
Cox Centralsmtp.central.cox.net (central users)
Cox Eastsmtp.east.cox.net (east coast users)
Cox Businesssmarthost.coxmail.com
Crosslinksmtp.crosslink.net
DCANETsmtp-relay.dca.net
Delmarva Onlinemail-gw.dmv.com
Delta Netsmtp.deltanet.com
Direcwaysmtp.direcway.com
DSL Extremesmtp.dslextreme.com
Earthlink Networkmail.earthlink.net or smtp.earthlink.net
Earthlink Network (International only)ismtp.earthlink.net
Edge.netmail.edge.net
Entersmtp.enter.net
EROLSmail.erols.com
Ezysmtp.ezy.net
Flashcommail.flashcom.net or smtp.flashcom.net
Frontline.netsmtp.fcc.net
Gateway.netsmtp.Gateway.net
GTImail.gti.net
HotMailmail.hotmail.com
IBM.Global netsmtp1.ibm.net
ioNet Incmail.ionet.net
Interaccess.comsmtp.interaccess.com
Internet Americamail.airmail.net
ITOLmail.itol.com
Junosmtp.juno.com
Mediacommail.mchsi.com
Mediaone.netsmtp.ce.medione.net
MegaPathmail.megapathdsl.net
MCImailrelay.mciworldcom.net or mailrelay.internetmci.com
Mindspringsmtp.mindspring.com
MSNsmtp.email.msn.com
Nauticommail.nauticom.net
Netcomsmtp.ix.netcom.com
Netcom (Canada)smtp.netcom.ca
Netscapesmtp.isp.netscape.com
NetZerosmtp.netzero.net
NYU.edusmtp.nyu.edu
OLG.commail.olg.com
Optimum Online Internet Service (optonline)mail.optonline.net
As of early 2010, OptOnline was not requiring that you sign into an account, but merely that you send out using their outgoing mail server. If when testing e-mail settings (in Outlook) you get the error “None of the authentication methods supported by this client are supported by your server” uncheck my outgoing server requires authentication.
Pacbellmail.pacbell.net
Patriot Mediasmtp.patmedia.net
Pipelinesmtp.pipeline.com
Prodigysmtp.prodigy.net
PSI.netrelay.smtp.psi.net
PTD.netpromail.ptd.net port 25
QISmail.qis.net
Qwest Internet Servicepop.dnvr.qwest.net
RCNsmtp.rcn.com
Rider.eduenigma.rider.edu
RoadRunnersmtp-server.<your-region> .rr.com
SBC Globalsmtp.sbcglobal.net
SBC Global Yahoosmtp.sbcglobal.yahoo.com
Smallville Communicationsmail.toto.net
SNiPmail.snip.net
Spectrum DSLmail.webstable.com
SprintLinksmtp.a001.sprintmail.com
Sprynetm6.sprynet.com
Starpowersmtp.starpower.net
Sympaticomailhost.sk.sympatico.ca
UMBCsmtp.gl.umbc.edu
USA.NETmail.netaddress.usa.net
US Internetsmtp.usit.net
UUNetmail.uu.net
Verizon Internet Servicesoutgoing.verizon.net or smtpout.verizon.net
Verizon may require the use of port 587
to send outgoing mail as well.
Wide Open Westsmtp.mail.wideopenwest.com
XO Communicationsmail.njd.xo.com or smtp.concentric.net
Yahoosmtp.mail.yahoo.com
Ziplinksmtp.ziplink.net
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Tom Hart

Tom Hart is a web developer and Constant Contact Certified Solutions Provider. Tom is also a photographer and his images have graced many websites.

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