Very useful to get reliable delivery, also on your own VPS. I use it for this and saved me a lot of the usual hassle. Supports unsubscribe links. Interesting, for clients, who use the server mail for sending mass emails.
I'm going to address the negative comments, none of which appear to have any substance.
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DJASTIAN:
This is about a different domain (SMTP.com) that is not owned by or affiliated with smtp2go. SMTP is an acronym for "Simple mail transfer protocol", a protocol that is not owned by one company.
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webdome: "SMTP2GO.com and SMTPCORP.COM are in fact one company"
It is in no way suspicious or unusual to own more than one domain.
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странный странник: "С адресов possible@smtp2go.com, make@smtp2go.com, ***** рассылается спам мошеннического содержания."
It is possible to send emails from any email address. You need to check the headers to find the actual origins of spam emails. Please see this article for details of how to find the sender of an email and to report spam: http://www.smtp2go.com/blog/how-to-effectively-report-spam/
They are using dirty promotion technicals in twitter:
SMTP COM Easy-to///////Use SMTP ServerTrouble Sending Email? Send Email Anywhere Worldwide! *****
Twitter page: https://twitter.com/#!/navyy8/status/90077623941730305