Outgoing Mail Server Connection Problems

Question

For the past two weeks, I have been unable to send any emails from my own webmail email address, [email protected] using Mail. I have checked with my ISP to make sure that all of my port settings are correct, I have made sure that firewall is turned off, I have checked using the Network Utility to make sure that I can successfully connect to my mail server (mail.amandafiedler.com). I have deleted my account and started over. Not sure what the problem is. I can receive mail, I just can't send anything! Help! Any other suggestions?

Answer 1

Turn your firewall back on! Firewalls prevent uninvited inbound traffic from entering/attacking your computer. If not at your computer, at least at your DSL/cable modem. You do not need your firewall turned off or any ports open to send mail, or to retrieve mail (because retrieved mail traffic will be "invited" traffic). In fact, the ports you specify in Mail (e.g., 25 for smtp, or maybe 443 (yes, I know that that is default for https web traffic but I think I recall hearing about some authenticated smtp servers using 443) or 587 for SSL-enabled smtp, 143 for imap, 993 for SSL-imap, 110 for pop, 995 for SSL-pop) are the port numbers AT THE SERVER, NOT the ports on your computer. Your computer just randomly chooses unused ports when sending stuff out. The only reason you need any ports on your computer open is if you are hosting services, like running your own website, or your own postfix mail server, or hosting gaming on your computer, so people can initiate requests to your host for services on those ports. So get that firewall back up!
Is your ISP the one that is providing you with the webmail service? Or is it a third-party mail provider? Sometimes, ISP's block any traffic destined for port 25 (outbound mail sent from your computer) unless it is going to smtp servers that they own. This is to try to prevent spammers from using their network to relay spam off of "foreign" smtp servers.
I get the impression that port 587 is sort of becoming the defacto smtp port at the mailserver for authenticated smtp service. AOL, for example, uses port 587 for smtp (send mail) because ISP's that block destination port 25 traffic that is not for that ISP's mailserver, will allow port 587 traffic because it is typically SSL-protected, password-authenticated smtp, that would be more readily identifiable back to you if you were spamming off of it.
So, make sure that when you talk to your ISP, if this mail service is NOT provided by them, find out whether they are blocking the port you are trying to use for smtp, but first, talk to your email provider (assuming they are not your ISP) and verify what smtp port they are using, doublecheck the smtp server host name (sometimes they are different than the hostname of where you connect to retrieve your mail), are they using SSL, are they password authenticated, and do they still allow email through anything other than a webmail interface?
Some mail providers also make you login to retrieve mail before you can send, too, so make sure that it is just not an operational issue of you trying to send mail before retrieving new mail, should they be operating that way.
Just out of curiosity, what happens in Terminal when you type
telnet {hostNameOfYourOutboundMailServer} {portNumberOfYourOutboundMailServer}?
Do you see something like :
Connected to {hostNameOfYourOutboundMailServer}.
Escape character is '^]'.
220 {hostNameOfYourOutboundMailServer} ESMTP Postfix
(you can type quit or just <control>-C to bail out of this)
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