I can't add the last Google Apps Email MX record because Zerigo DNS only allows 10 records. Will it matter?

I am using Heroku for my site hosting, and Zerigo for DNS开发者_如何学JAVA magagement. I'm trying to setup Google Apps email, but I can't add the last MX record (ASPMX5.GOOGLEMAIL.COM.) because I have hit my limit of 10 allowed total records on Zerigo. Will it matter if I don't add this last record?

No it won't. Google Apps gives you that many MX servers for heavy redundancy in case of problems. MX records have a server to send attempt to send mail to and a priority associated with it (IE which server are you in line to receive mail for this domain if the other isn't available). You weren't able to add the lowest priority server to your DNS. Normally no mail server would attempt to connect to it (aspmx5.googlemail.com) unless all the others were unavailable. In an instance like that we'd probably have bigger problems to worry about :)

It's very unlikely that it will matter. Each DNS record is given a priority, so whenever an email server is resolving that domain name, it will go through each record, order by priority in ascending order, until it finds one that resolves.

Google's servers are very stable, so if they're to the point that 9 previous records are failing, chances are good that it's catastrophic and your email will be down regardless of DNS.

tl;dr: you're fine