The short answer
MX Guarddog suits small offices that want basic inbound spam and virus filtering for as little money as possible, with a free first month, a 60-day refund and a 7-day outage queue. iBlockSpam suits businesses with more mailboxes or aliases, or that want more than inbound filtering for the price: an outbound relay, DNS drift alerts, Lookalike Domain Watch, DMARC monitoring, a guided setup wizard and digests as often as hourly.
If you have 10 mailboxes and only need inbound filtering, MX Guarddog will cost you less. We'd rather say that plainly than have you find out later.
Competitor details below were checked on MX Guarddog's own pages in October 2026.
Side by side
| Item | MX Guarddog | iBlockSpam |
|---|---|---|
| Pricing model | $0.25 per email address per month; user aliases and domain aliases free | Per domain, unlimited mailboxes (mailbox count, not message volume) |
| Published price | Yes, $0.25 per address; billed in tokens, which you can buy or earn by linking to MX Guarddog | Protect $12 per domain/month billed annually ($144/year) or $15 month-to-month; Protect Plus $19 annually or $24 monthly. Beta pricing, USD, excluding tax |
| Message volume | No limit on messages received | 100,000 inbound messages per domain per month included |
| Maximum message size | 34.22 MB | 400 MB |
| Trial or guarantee | First month free (vendor says no payment card is needed); refunds on purchases in the last 60 days | No free trial; 30-day money-back guarantee on a domain's first annual subscription |
| Contract | No long-term contract | Annual or month-to-month; cancel any time in the billing portal, effective at period end |
| If your server is down | 7-day (168-hour) delivery queue | Mail spooled for up to 5 days, then delivered |
| Quarantine reports | Reports to every user, preferences set by the user; the FAQ describes daily reports | Personal quarantine for every user; digests hourly, daily, on a chosen weekday or custom; shared admin quarantine |
| Outbound mail | No outbound relay found on the pages we checked | Outbound relay with DKIM signing and outbound filtering, 500 messages a month |
| Directory sync | Active Directory, LDAP and cPanel address sync | Not offered; unlimited mailboxes means you don't count addresses |
| Pre-cutover test | Send a test message directly to its servers before switching MX | Setup verifier for MX routing and outgoing SPF, DKIM and DMARC; guided wizard with before/after DNS and rollback steps |
| Uptime commitment | 99.95% SLA with service credits | No SLA with credits; a public status page with an end-to-end mail-flow probe |
| Monitoring and tools | Not listed on the pages we checked | Domain monitoring, Lookalike Domain Watch, DMARC monitoring and free DNS tools |
What it costs at 10, 48 and 100 mailboxes
Assumptions: one domain, every mailbox is a separate address (aliases are free on both), published prices only, USD, excluding tax.
| Item | 10 mailboxes | 48 mailboxes | 100 mailboxes |
|---|---|---|---|
| MX Guarddog | $2.50/month | $12.00/month | $25.00/month |
| iBlockSpam Protect, annual | $12/month ($144/year) | $12/month ($144/year) | $12/month ($144/year) |
| iBlockSpam Protect, month-to-month | $15/month | $15/month | $15/month |
| iBlockSpam Protect Plus, annual | $19/month ($228/year) | $19/month ($228/year) | $19/month ($228/year) |
Below 48 addresses, MX Guarddog is cheaper than iBlockSpam on price alone. At 48 they match against Protect billed annually, and against month-to-month Protect the break-even is 60 addresses. iBlockSpam's price also covers the outbound relay, monitoring and DMARC reporting, so compare what you'd otherwise pay for those.
When MX Guarddog is the better choice
- You have a small team and a tight budget. At $0.25 per address, a 10-person office pays $2.50 a month.
- You want to try before paying. MX Guarddog's first month is free, and it refunds purchases made in the last 60 days. iBlockSpam has no trial; its guarantee covers 30 days on a first annual subscription.
- You need a longer outage buffer. MX Guarddog's 7-day queue is longer than iBlockSpam's 5-day spooling.
- You want a written SLA with credits. MX Guarddog publishes a 99.95% uptime commitment. iBlockSpam doesn't offer an SLA with credits today.
- You sync addresses from Active Directory, LDAP or cPanel. MX Guarddog can import valid addresses automatically.
When iBlockSpam is the better choice
- You have about 50 or more mailboxes. Per-domain pricing stops growing with headcount, and aliases are unlimited too.
- You send mail through a relay. iBlockSpam includes an outbound relay with DKIM signing and outbound filtering.
- You receive large files by email. iBlockSpam accepts inbound messages up to 400 MB; MX Guarddog's limit is 34.22 MB.
- You want users to see held mail more than once a day. Digests can run hourly, daily, on a chosen weekday or on a custom schedule.
- You want to watch your domain, not just filter it. Domain monitoring alerts you when MX, SPF or DMARC change, Lookalike Domain Watch looks for look-alike domains, and DMARC monitoring shows who sends mail as your domain.
- You want a guided setup for your platform. Step-by-step setup for Microsoft 365, Google Workspace, cPanel/WHM and Exchange Server, with rollback steps.
How to switch from MX Guarddog
- Export your allowed and blocked senders from MX Guarddog.
- Save your current DNS with the Email Health Check and lower the MX TTL a day or two ahead.
- Add your domain in iBlockSpam and follow the guided setup for your platform.
- If your mail server only accepts inbound mail from MX Guarddog's servers, allow iBlockSpam's servers before you change MX.
- Change MX, test with the Email Header Analyzer, and keep MX Guarddog active until the old TTL has passed and no new mail arrives there.
Our migration plan covers each step and the rollback, and the guide to switching spam filter providers explains the common pitfalls.
MX Guarddog is a trademark of its owner; iBlockSpam is not affiliated with MX Guarddog.
Sources
Checked October 2026.
- MX Guarddog: pricing ($0.25 per address, free aliases, no message limit, first month free, 60-day refunds)
- MX Guarddog: home page (168-hour spooling, quarantine reports, AD/LDAP/cPanel sync, 99.95% SLA, in operation since 2006)
- MX Guarddog: technical FAQ (7-day delivery queue, 34.22 MB maximum message size, daily quarantine reports)
- MX Guarddog: pre-sales FAQ (test delivery before going live, no relay to external domains)
- MX Guarddog: billing FAQ (tokens, earning tokens with links)
- MX Guarddog: service level agreement (99.95% uptime commitment and service credits)
Frequently asked questions
Is MX Guarddog cheaper than iBlockSpam?
For most small offices, yes. MX Guarddog charges $0.25 per email address a month, so 10 addresses cost $2.50 a month. iBlockSpam Protect is $12 per domain a month billed annually, whatever the mailbox count. MX Guarddog stays cheaper up to about 48 addresses; the two cost the same at 48, and iBlockSpam costs less above that.
How long does MX Guarddog keep mail when my server is offline?
MX Guarddog advertises 168-hour spooling, and its technical FAQ describes a 7-day delivery queue that retries every 15 minutes. iBlockSpam spools for up to 5 days. If longer outages are a real risk for you, MX Guarddog's window is longer.
Does MX Guarddog filter outgoing mail?
We didn't find an outbound relay or outbound filtering service on MX Guarddog's pricing and FAQ pages in October 2026; its FAQ says its servers won't relay mail to outside domains. iBlockSpam includes an outbound relay with DKIM signing and outbound filtering, 500 messages a month per domain.
Can I test MX Guarddog before changing my MX records?
Yes. MX Guarddog's pre-sales FAQ explains how to send a test message straight to its servers before the switch. iBlockSpam's setup verifier checks MX routing and your outgoing SPF, DKIM and DMARC once you start setup, and our migration plan includes rollback steps.
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