The most common way for a mail client program to send e-mail is using port 25,
which is also the port used by mail servers to talk to each other. But port 25 is widely
abused by malware to spread worms and spam. As a result, many ISPs are restricting its use.
It is very common for many ISPs to restrict the use of port 25 by limiting the user.
For example AOL offers no email sending options for many of its users and if they do its
common for them to block port 25 completely. In addition most ISPs limit you to the number
of emails you can send per hour. This varies from company to company and its best to
contact your ISP and ask them what their email sending limits are.
There are a few potential solutions. If you want to use your company's mail server,
perhaps you should be using a virtual private network to connect to the company network
and mail through that. The other mail server may also support web mail, and since all
that goes through port 80 (the http port) the ISP won't block it.
But there is another SMTP submission port, port 587, which almost all mail server
supports. In fact, according to the relevant standard, port 587 is the preferred port
for mail submission. For our customers we can provide a
port 587 mail server that can bypass
your ISP. Note ourmail servers
are used only for permission based email lists and can not
be used for sending spam! For more information and pricing for our port 587 mail servers
click here.
