Common queries of Outlook Email Sending Issue

Common queries of Outlook Email Sending Issue

Postby Prasad » June 9th, 2013, 12:11 am

Have you ever wondered what happens when you press the Send button in your email program? Probably not, I guess — as long as it works. This is exactly the reason why you should wonder, though. In case something doesn't work it's good to know what does not work.

When you send email SMTP comes into play. SMTP is short for Simple Mail Transfer Protocol as defined in RFC 2821: Simple Mail Transfer Protocol. Your mail client talks to the SMTP server using this clean and simple procedure to get email from one place to another.

The original/legacy email port, 25 (Outgoing Port), has been in use since the inception of email and has limited or no security features. As a result, port 25 has been used for the transmission of spam and malware :evil: from infected computers (intentionally or unintentionally). Also this results in blacklisting our IP address due to spam mails sent by client which in turn blocks certain contents on the Internet for such blacklisted IP address i.e. finally our Retail customer faces problem while browsing websites. Hence to overcome this, Port 25 is being blocked for all our Retail customers (i.e. DHCP users).

Who will be affected?
1. Retail customers sending mail through a 3rd party mail server with a mail client like Outlook, Outlook Express, Thunderbird or Mac Mail
2. Customers that send mail through their company mail server and they do not use a VPN
3. Customers running their own mail server locally for outbound traffic.

Note: With Exchange Server Account you will not faced any issue as Outlook can connect to Exchange through the Internet by using remote procedure call (RPC) over HTTP.
(Refer post

Alternate Solution:
By Default, Email software will set the SMTP 'port to '25', which is the standard port for the SMTP protocol. However we have allowed alternative ports that you can send through, provided same has been also allowed from your Email Admin.
These are: 587 or 465 ( For port configuration refer

Port 587 is reserved for email message submission and is preferred as specified in document Port 587 provides additional security as the data between your Mail client and server is encrypted.
While most email clients and servers can be configured to use port 587 instead of 25, there are cases where this is not possible or convenient.

If this does not work for you due to limitations from your Email Admin then still there are alternate solutions,
1. Use Public VPN service
You may try with various Public VPN services as long as they offers port 25 open on their servers.

2. Use Public SMTP server
Relaying or using free public SMTP server allows you to send email through an external mail server :idea: ,
e.g. google SMTP server for more information refer,

With this option, email looks as if it’s coming from your own domain. For example, I can send an email from to anythingelse via an intermediate host without the YahooMail user knowing about the intermediary (unless he/she looks at the headers). This functionality having some limitations.

3. Upgrade to Static IP
In case of our SMB/LL/VILL/Static IP (Value add Service) subscribed customer there is no such port blocking and with such customers if any spamming done only that customer IP will get blacklisted where as rest of our Retail clients will enjoy net browsing.

For any information of Static IP Value Add service subscription, Please feel free to contact our toll free 1800-20-94276 .
Prasad Bhatte
Posts: 28
Joined: November 16th, 2012, 3:57 pm
Location: Mumbai

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