The charity opted for a hosted application from supplier Mimecast to support the London headquarters of its UK and Republic of Ireland arm, and the 18 divisions that make up the organisation.
The Salvation Army's IT resources were coming under tremendous strain trying to purge large volumes of spam from 3,000 user email accounts, according to UK chief information officer (CIO) Martyn Croft.
"A couple of years ago we were experiencing spam levels in the order of 90 per cent, and like everybody else in the world you have to deal with that," he said.
"We have a fairly serious investment in IT, what with finance systems, HR, payroll, property management and fundraising systems, with donors and supporters to support."
The organisation made what Croft thinks is a fairly logical decision.
"If we could put that spam-filtering in the cloud, alongside a much cleaner feed, we'd get better network bandwidth use," he said.
"So we had a look around and we did a few tests, and found that Mimecast was the best."
One of the things that interested Croft about the service was its email archiving feature, not only across the gateway, but also the fact that it supports the Lotus Notes system used by The Salvation Army. "Few people can do that," he said.
"At the minute, we haven't taken up email archiving yet, because I think email archiving brings with it a whole set of questions that the organisation has to look at and examine closely before it dives into that," he added.
Croft liked the way the software searched through emails, and the relative ease with which it tracked them in and out of its organisation.
"Also, the reporting was quite good compared with the other products, and the interface is pretty slick," said Croft.
"A couple of pretty cool features about the Mimecast system really swung the deal in the end."
One of the features Croft highlights is Strip and Link for handling large email attachments. Some employees working in the fundraising or publishing areas need to send and receive very large files that consume a lot of bandwidth. Strip and Link stops large attachments from clogging up the email server and using too much bandwidth, because it holds the attachment and just forwards a link from which users can download.
Another critical feature is closed-circuit messaging, which facilitates a secure email dialogue, allowing the charity to deal with sensitive and confidential data.
"Our homelessness service means we have to deal with a lot of vulnerable people, and their details are precious, and what we don't want to see is information like this sent around as plain-text emails," said Croft. "Mimecast gives us an element of data leak protection with this feature, and allows us to establish those encrypted channels."
The Salvation Army has an annual turnover of £225m and about 7,000 staff. About 1,500 of these are ordained ministers, with the rest being ordinary employees – so-called lay staff. Alongside its evangelical work, the charity runs 120 social centres - typically homeless shelters, old people's homes and drink rehabilitation centres.