Mar 27, 2026 - For details about updated CVE-2025-53521 (BIG-IP APM vulnerability), refer to K000156741.

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a_basharat_2591's avatar
a_basharat_2591
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Apr 29, 2019

SMTP [port25] VS configuration

Hi, I need to configure an SMTP [port 25] Virtual Server. I am used to configure VSs on port 443, my question regarding the new VS for SMTP is what I need to configure on the 'Configuration' section ...
big-ip
devops
LTM
security
Per_Hagstrom_71's avatar
Per_Hagstrom_71
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Apr 29, 2019

It might depend on how you want the SMTP traffic to work.

 

In my case with an Exchange 2016 server, the "default" SMTP setup caused us to not see the originating client IPs, which is a big deal for us, and since it's not HTTP/S traffic, X-Forwarded-For is of no help. I did get it to work by changing the Type to 'Performance (Layer 4)', and creating a fastL4 Protocol Profile (Client), and setting it to 'Loose Close: Enabled'

 

Source Address Translation: None

 

Source Port: Preserve Strict

 

Hope that helps?

 

a_basharat's avatar
a_basharat
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Apr 30, 2019

The client said to me "For Hybrid connections SMTP over TLS is used, certificates are used on both sides over port 25". An explanation is provided here -

 

According to that which option mentioned on the deployment guide [out of the 6 explained, page 3] we should be implementing?