Which port does sendmail use

I have been using sendmail to send out mails using internally available mail server. But currently port 25 is blocked for security reasons. I would like to know if there is a way to specify port number in the sendmail utility. I was not able to find anything in the man pages for sendmail. Is there any alternate utility that could do this? You can route mail using other ports, or even other protocols than SMTP but that will typically only work within your own network.

The mailservers from your intended recipients will most likely only accept incoming email via SMTP on port For instance when I configure sendmail to listen to port it will typically only accept incoming e-mail over that port when the user has authenticated. Relay servers may check content viruses, spam or enforce policies adding the standard disclaimer, archiving messages for compliance, restricting recipients etc. The assumption is that sendmail forwards all your email traffic to the relay which transports the messages to the intended recipients and the relay server not requiring authentication.

To route some email domains to one remote TCP port and mail for other domains to another requires some editing in the sendmail. Copy the settings from the existing esmtp mailer and add a port number:. The line above will allow sendmail to look up the MX records for example. The brackets tell sendmail to ignore possible MX records for smtp. Sendmail FAQ 3. Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group.

Create a free Team What is Teams? Learn more. Using port with sendmail Ask Question. Asked 7 years, 5 months ago. Active 6 years, 3 months ago. Replace smtp. How to configure sendmail to use a remote smtp server that requires authentification and how to test authentication? Does it require any authentication before connecting to local smtp server. If authentication is required, please get all detail credentials. To give you the knowledge you need the instant it becomes available, these articles may be presented in a raw and unedited form.

Environment Red Hat Enterprise Linux 5. Received the following error while testing a mail delivery : user xxxx. Connecting to smtp. Deferred: Connection reset by smtp. Port 25 is blocked at mail server, it only accepts port Setup requirement in this server is, This server Local sendmail server will receive mails from internal application SAP via port This service is only implemented in the more recent verions Windows starting with Windows and Windows XP.

To configure sendmail daemon to listen on a different port say than port 25, follow these steps. SSL is commonly used for encrypting communications over the internet.

When an email client or outgoing server is submitting an email to be routed by a proper mail server, it should always use SMTP port as the default port.