Same as for the Process Center (question 3129): the SMTP settings are in the server's 100Custom.xml (Process Server: <profile>/config/cells/<cell>/nodes/<node>/servers/<server>/process-server/config/100Custom.xml) - one file per cluster member, or once at the cell/cluster level (.../cells/<cell>/clusters/<cluster>/process-server/config/100Custom.xml, BAW 20+ supports the cluster scope):
<properties>
<server merge="mergeChildren">
<email merge="mergeChildren">
<mail-server-address merge="replace">smtp.example.com</mail-server-address>
<mail-server-port merge="replace">25</mail-server-port>
<default-from-address merge="replace">workflow@example.com</default-from-address>
<valid-from-required merge="replace">false</valid-from-required>
<mail-server-user merge="replace">smtpuser</mail-server-user> <!-- optional, authenticated relay -->
<mail-server-password merge="replace">{xor}...</mail-server-password>
</email>
</server>
</properties>After the change: full synchronisation of the nodes (deployment manager > nodes > Full resynchronize) and a restart of the Process Server cluster members - the file is read at start-up only. On BAW 20.0.0.1+ the settings can also be changed without editing XML: Process Admin console > Server Admin > Admin Tools > Server settings exposes the e-mail section, and BPMConfig -update -de ... -properties with bpm.de.emailServer* keys does it scripted. On CP4BA the same keys go into the 100Custom.xml ConfigMap referenced by the BAW custom resource (bpm_100Custom_xml_secret_name / custom.xml settings).
Test: run the System Data Send E-Mail service from Process Designer against that server (the designer's playback runs on the Process Center, so for a real Process Server test start a small process there).
References