Changes needed after ISP switch

[cah]

ISPs have their own SMTP servers and they may use different ports. In the past, they just use port 25 but had enforced security by using SSL or TLS and they have different ports. For example, Verizon and Frontier use SSL/TLS pver port 465 for encryption. Spectrum/Charter/Time Warner/Road Runner is using STARTTLS over port 587.

In order for the mail server (sendmail) to work, the following items may need to be updated first:

1. Stunnel (Only if ISP is forcing port 465)
   /etc/stunnel/stunnel.conf
2. Sendmail
   /etc/mail/auto/client-info (the hash db file is needed)

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   AuthInfo: "U:<ISP username>" "I:<ISP username>" "P:<ISP password>"
   

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   makemap hash client-info < client-info
   

When ISP is using port 587, there's no need to use stunnel for encryption.
Just make sure the following settings in sendmail.mc:

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define(`SMART_HOST', `<ISP SMTP server>')dnl
define(`RELAY_MAILER_ARGS', `TCP $h 587')
define(`ESMTP_MAILER_ARGS', `TCP $h 587')

Use m4 to generate a new sendmail.cf:

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m4 sendmail.mc > sendmail.cf

Restarted sendmail and all worked.