Here are a couple of the most frequently asked questions on this subject:
Question: I installed version 1.1 of the MTA but now some mail messages are coming in as a file attachment with an attachment name of "att1.unk".
Answer: The reason is that some mailers inappropriately send messages with a Content-Type of "Plain/Text" (Netscape is the most frequently used mailer that does this) but without a Content-Name; plain text messages should not be specified with this MIME Content-Type attribute. If you want to go back to the way SMTP 1.0x handled it, set "SMTPMTA_INLINE_TEXT_ATTACHMENTS=1" in your notes.ini file.
Question: How do you tell the SMTP MTA to use '.' instead of '_' for space replacements in user names?
Answer: Add "SMTPMTA_SPACE_REPL_CHAR=." to your notes.ini file. You have to make sure your user names do not contain any periods if you use this translation of spaces.
Question: How do you prevent spammers from using your SMTP MTA to send their junk through?
Answer: Add "SMTPMTA_REJECT_RELAYS=1" to your notes.ini file. You can also set "SMTPMTA_HELO_DOMAIN_VERIFY" to a non-zero value to verify that the SMTP mailer represents the domain they claim to be from. And finally, you can set "SMTP_MTA_DENIED_DOMAINS" to point to a text file with a list of domains you want to reject mail from. Note that this only works with Notes 4.6. More information can be found in Technote 159050 in the Notes Knowledge Base.
If you are running SMTP MTA 1.2, you can use "SMTPMTA_HELO_DOMAIN_VERIFY=1" to make sure that the connected SMTP server identifies itself properly (spammers will pretend they are someone else). You can also use "SMTPMTA_DENIED_DOMAINS=<filename>" to specify a newline-separated list of domains that should not be allowed to send mail to your SMTP MTA.
Question: How do you set the default line length for incoming and outgoing mail?
Answer: Add "SMTPMTA_Outbound_Line_Length=xx" to your notes.ini file, where xx is the line length (default is 75). You can also set "SMTPMTA_Inbound_Line_Length=xx" for incoming mail.
Question: How do you make the SMTP MTA check that the omsgcnv and imsgcnv processes haven't stopped?
Answer: If you add "SMTPMTA_ENABLE_STARTUPCHECK=1" to your notes.ini file, it will check for all 5 SMTP processes every half hour and restart any dead ones. This only works in Notes 4.6.
Question: Can you tell the SMTP MTA to use a different port than 25?
Answer: In Notes 4.61 and above, you can add "SMTPMTA_IPPORT=xxxx" to your notes.ini file. This will set the SMTP MTA to use port xxxx.