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Community Member

Need Allowing SMTP traffic from my network only BLOCK outside network to used SMTP.

Dear Experts,

I have facing very much problem of SMTP traffic , lots of unknown outside the network used my mail server SMTP port,

heavy much mail send through my mail server ( used SMTP port) from outside network.

I need it to block smtp port from outside network , only allowed from my network.

i am using Cisco 3845 router.

my Mail server IP 120.111.234.4

If I put in access lists for each range and nothing else associated with SMTP would that accomplish the task?

Allowing SMTP traffic from on a few IP ranges ( my network only BLOCK outside network need to configure my Cisco 3845 to only allow SMTP traffic from certain IP ranges to my mail server

so what i can do to solve this issue.

my network 120.111.234.0/22

                   221.212.142.0/24

                   210.212.152.0/25

So plese give me the soluction regarding the same.

Any help would be great!

Thanks,

Vaib...

Allowing SMTP traffic from on a few IP ranges

5 REPLIES
Cisco Employee

Re: Need Allowing SMTP traffic from my network only BLOCK outsid

You would need to configure your mail server to not allow mail relay through it.

Don't think you can block mail traffic from outside with an access-list, as it will block legitimate mail traffic inbound.

Community Member

Re: Need Allowing SMTP traffic from my network only BLOCK outsid

Dear Halijenn,

I already congured in my mail server ( no mail relay). but still facing the problem i need to block smtp through outside the network.

Thanks in ADV,

Vaib...

Cisco Employee

Re: Need Allowing SMTP traffic from my network only BLOCK outsid

You would need to have Mail gateway, like Iron Port or CSC module on ASA firewall for example to be able to block those traffic. With access-list, you would be blocking legitimate mail traffic as well because access-list only looks at layer 3/4, not deep into the email itself.

Community Member

Re: Need Allowing SMTP traffic from my network only BLOCK outsid

Dear Friend,

I need to config in my router SMTP port not allowed to used of outside the network , it;s only allowed my network ips only. other ips block to used SMTP

Thanks,

Vaib...

Hall of Fame Super Gold

Re: Need Allowing SMTP traffic from my network only BLOCK outsid

Do you understand how email in the internet works ?

Are you able to configure correctly an email server ?

From your posts above, seems like the answer to both questions is "no".

In that case, I recommend you engage a reputable IT professional to help you.

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